Engineering 
Library 


THE 
POPULAR  CHEMICAL  DICTIONARY 


THE    POPULAR 
CHEMICAL  DICTIONARY 

A   COMPENDIOUS   ENCYCLOPAEDIA 


BY 

C.    T.    KINGZETT,    F.I.C.,    F.C.S. 

AUTHOR  OF 

"THE  HISTORY,  PRODUCTS,  AND  PROCESSES  OF  THE  ALKALI  TRADE"  (LONGMANS); 
"ANIMAL  CHEMISTRY;  OR,  THE  RELATIONS  OF  CHEMISTRY  TO  PHYSIOLOGY 

AND  PATHOLOGY  "  (LONGMANS)  ; 

"NATURE'S  HYGIENE  AND  SANITARY  CHEMISTRY"  (BAILLIERE,  TINDALL  AND  cox); 
"CHEMISTRY  FOR  BEGINNERS  AND  SCHOOL  USE"  (BAILLIERE,  TINDALL  AND  cox), 

ETC.,  ETC.; 
PAST  VICE-PRESIDENT,  SOCIETY  OF  PUBl.IC  ANALYSTS  ;  AND  ONE  OF  THE  ORIGINAL 

FOUNDERS    OF   THE    INSTITUTE    OF    CHEMISTRY 


SECOND    EDITION 


NEW  YORK 

D.  VAN  NOSTRAND  COMPANY 

EIGHT  WARREN  STREET 

1921 


Engineering 
Library 


There  is  a  lesson  in  each  flower, 
A  story  in  each  stream  and  bower  ; 
On  every  herb  o'er  which  we  tread 
Are  written  words  which,  rightly  read, 
Will  lead  us  from  earth's  fragrant  sod 
To  hope  and  holiness  and  God." 


PRINfED    IN    GREAT    BRITAIN. 


PREFACE  TO  THE  SECOND  EDITION 

THE  very  favourable  reception  accorded  to  the  first  edition 
of  this  work  has  induced  me  to  enlarge  its  scope,  thus  permit- 
ting of  the  inclusion  of  many  more  natural  products  and 
manufactured  articles  and  fuller  references  to  a  number  of 
subjects  which  are  of  special  present-day  interest  and  import- 
ance, such  as  the  Hypothetical  ^Ether,  Atomic  Structure, 
Catalysis,  Colloids,  Constitution  of  Matter,  Cottrell  Precipita- 
tion Process,  Enzymes,  Flotation  Process  of  Ore  Dressing, 
Lubricants,  Nitrogen  Fixation,  Plant  Colouring  Matters, 
Radio-activity,  Refractories,  etc. 

All  criticisms  of  the  original  work  have  received  careful 
attention,  and  it  has  been  thoroughly  revised  and  brought  up 
to  date,  many  chemical  constants  being  introduced,  so  that  it 
may  be  of  increased  usefulness  to  practical  chemists  for 
reference  purposes,  without  diminishing  its  value  in  other 
respects.  In  brief,  I  have  endeavoured  to  make  the  volume 
a  compendious  encyclopaedia  of  chemical  information,  of 
service  to  professional  chemists  by  reason  of  its  comprehen 
sive  character  and  scientific  accuracy ;  useful  to  merchants, 
brokers,  and  all  others  who  have  to  deal  with  chemical, 
manufactured  and  natural  articles ;  and,  while  I  am  conscious 
of  many  imperfections  in  carrying  out  what  has  proved  to  be  a 
heavy  and  difficult  task,  I  trust  it  is  qualified  by  its  informative 
character  to  find  a  place  in  the  libraries  of  all  who  take  an 

v 

481594 


vi  PREFACE  TO  THE  SECOND  EDITION 

interest  in  the  arts  and  industries  of  the  British  Empire, 
and  the  utilization  of  its  boundless  resources  upon  which  the 
future  prosperity  of  that  Empire  so  largely  depends. 

I  have,  of  necessity,  culled  information  from  all  sorts  of 
sources,  including  standard  works,  the  publications  of  scientific 
societies  and  the  chemical  press  generally,  for  which  I  make 
grateful  acknowledgment,  as  also  to  Messrs.  John  J.  Griffin 
and  Sons,  John  Browning,  and  L.  Oertling,  Ltd.,  for  the  use 
of  printing  blocks  illustrative  of  apparatus. 

C.  T.  KINGZETT. 

"NEWLANDS," 
WEYBRIDGE. 

August,  1921 


PREFACE  TO  THE  FIRST  EDITION 

IN  the  compilation  of  this  dictionary,  I  have  attempted  to 
discharge  a  task  which  has  not,  to  my  knowledge,  been  pre- 
viously undertaken,  and  that  is,  to  give  in  one  volume,  in 
compendious  form,  and  in  simple  language,  descriptions  of 
the  subjects  of  chemistry — its  laws  and  processes,  the  chemical 
elements,  the  more  important  inorganic  and  organic  com- 
pounds and  their  preparation  or  manufacture  and  applications, 
together  with  illustrated  descriptions  of  chemical  apparatus. 

My  endeavour  has  been  to  produce  a  popular  educational 
work  which  will  incidentally  serve  as  an  advanced  companion 
to  my  little  book  entitled  "  Chemistry  for  Beginners  and 
School  Use"  (Bailliere,  Tindall  and  Cox),  and  as  a  general 
work  of  reference,  not  only  to  many  practical  chemists,  but 
more  particularly  to  that  larger  body  of  the  public  who,  in 
course  of  their  various  callings,  have  occasion  to  deal  or  take 
interest  in  the  thousand  and  one  subjects  and  substances  of 
which  descriptions  are  given. 

While  abstaining  from  giving  references  and  quoting 
authorities,  in  order  to  avoid  confusion,  I  gratefully  acknow- 
ledge the  use  made,  in  particular,  of  Newth's  "  Text-book 
of  Inorganic  Chemistry"  (Longmans,  Green  and  Co.) 
Sudborough's  translation  of  Bernthsen's  "  Textbook  of 
Organic  Chemistry"  (Blackie  and  Sons,  Ltd.),  Watts' 


viii  PREFACE  TO  THE  FIRST  EDITION 

"  Dictionary  of  Chemistry  "  (Longmans  and  Co.),  and  Tilden's 
most  interesting  work  entitled  "  Chemical  Discovery  and 
Invention  in  the  Twentieth  Century"  (George  Routledge  and 
Sons,  Ltd.). 

Mr.  F.  G.  Clarke,  B.Sc.,  has  kindly  assisted  me  in 
correcting  the  proof-sheets,  and  my  thanks  are  due  to  Messrs. 
John  J.  Griffin  and  Sons,  Messrs.  Baird  and  Tatlockj  John 
Browning,  and  L.  Oertling,  for  the  loan  of  printing  blocks 
illustrative  of  chemical  apparatus. 


C.  T.  KINGZETT. 


"  MAPLIN," 

FRINTON-ON-SEA; 
November,  1919. 


CHEMICAL    DICTIONARY 


ABIETIC  ACID  (C19H28O2)— A  constituent  of  common  rosin 
which  crystallizes  in  small  plates,  melts  at  153°  C.,  and  is 
soluble  in  hot  alcohol,  ether,  and  chloroform.  Pimaric  acid 
(C20H30O2),  obtained  from  galipot  (French  rosin),  melts  at 
145°  C.,  and  nearly  resembles  abietic  acid. 

ABRASIVES — Preparations  such  as  aloxite,  carborundum, 
corundum,  emery,  kieselgiihr,  pumice  powder,  tripoli, 
oilstone,  and  whetstone,  used  for  cleaning  or  abrading  by 
rubbing.  Emery  in  the  raw  state  comes  from  the  Island 
of  Naxos,  in  the  Greek  Archipelago ;  silicon  carbide, 
corundum,  and  corundite  are  found  in  South  Africa;  and 
an  aluminous  abrasive  is  found  in  the  south  of  France 
and  the  Pyrenees.  All  are  used  in  making  grinding- 
wheels,  etc. 

ABSINTHE — A  bitter  and  drink,  used  in  France  and  Switzer- 
land, prepared  from  various  species  of  Artemesia  absin- 
thium (wormwood),  which  also  yield  absinthe,  or  wormwood, 
oil.  The  unexpanded  flower-heads  of  another  variety 
(Artemesia  vahliana)  are  the  source  of  santonin.  A  substance 
named  absinthin  (C40H56O8.H2O)  is  said  to  constitute  the 
bitter  principle  of  wormwood,  and  is  a  crystalline  body, 
slightly  soluble  in  water  and  readily  soluble  in  alcohol. 
Absinthe  oil  has  a  sp.  gr.  of  0-92  to  0-955;  a  refractive 
index  of  1-46  to  1*47,  and  is  soluble  in  alcohol,  ether,  etc. 

ABSORBENT — The  property  of  absorbing  or  soaking  up. 

ABSORPTION  BULBS— See  Organic  Analyses. 

ACACIA— See  Gums. 

ACANTHITE— Natural  silver  sulphide  (Ag2S),  containing 
87  per  cent,  silver,  found  in  Colorado. 

ACETALDEHYDE— See  Aldehydes. 

ACET AMIDE— See  Amides.. 

ACETANILIDE  (C8H9NO),  or  PHENYLACETAMIDE 
(C6H5.NH.C2H3O)— A  white  crystalline  substance  known 
under  the  common  name  of  "  antifebrine,"  and  used  as  a 
medicine  in  fever  cases.  It  is  made  by  boiling  aniline  with 
glacial  acetic  acid.  Melting-point,  113°  C. 


/,  5  J  •{?•**  .°'Va  2  ••>    2  A  " 
•  !"•*   :2lu« 


ACETIC  ACID  (C2H4O2)—  The  active  principle  of  vinegar, 
which  contains  from  3  to  5  per  cent.  It  is  readily  pre- 
pared by  the  oxidation  of  ordinary  alcohol  and  the 
fermentation  of  alcoholic  liquids  by  a  minute  organism 
(Mycoderma  aceti).  It  is  also  extracted  from  the  products  of 
the  dry  distillation  of  wood.  (See  Pyroligneous  Acid.) 

Pure  acetic  acid  (also  known  as  glacial  acetic  acid)  is  a 
crystalline  body  of  sp.  gr.  1*055  which  melts  at  167°  C., 
boils  at  118°  C.,  and  is  soluble  in  water  and  alcohol. 

What  is  known  as  the  "quick  process"  of  producing 
ordinary  acetic  acid  consists  in  trickling  dilute  alcoholic 
liquors  over  shavings  of  beech-wood  previously  coated 
with  "mother  of  vinegar"  —  that  is,  a  cultivation  of  the 
Bacterium  aceti  —  at  a  temperature  of  35°  C.  The  souring 
of  thin  wines  is  due  to  the  production  of  acetic  acid  by 
the  same  micro-organisms,  which  are  always  present  in 
the  air.  , 

A  process  for  the  production  of  acetic  acid  from  acety- 
lene is  as  follows  :  calcium  carbide  is  prepared  by  heating 
lime  with  coke  in  an  electric  furnace,  and  the  acetylene 
produced  from  this  product  is  then  combined  with  water, 
through  the  agency  of  sulphuric  acid  acting  in  conjunction 
with  mercuric  and  ferric  sulphates,  whilst  the  aldehyde  is 
oxidized  by  means  of  oxygen  distilled  from  liquefied  air 
These  changes  may  be  expressed  as  follows  : 

1.  The  production  of  acetylene  from  calcium  carbide  — 

CaC2  +  2H20  =  C2H2  +  Ca(OH  )2. 

2.  The  hydration  of  acetylene  to  acetaldehyde  — 

C2H2  +  H2O  =  CH3.CHO. 

3.  The  oxidation  of  the  acetaldehyde  to  acetic  acid  — 

CH8.CHO  +  O  =  CH3COOH. 

From  the  acetic  acid  thus  prepared  acetone  can  be  pro- 
duced by  the  reaction  expressed  by  — 

2CH3COOH  =  (CH3)2CO  +  C02  +  H2O. 
(See  Acetone.) 

Acetic  acid  in  its  various  forms  finds  large  applica- 
tion in  industrial  processes,  including  that  of  white-lead 
manufacture,  and  for  technical  purposes  it  is  put  on  the 
market  in  liquid  forms  containing  respectively  33,  70,  and 
80  per  cent.,  etc.  (See  Wood.) 

By  combination  with  bases,  acetic  acid  forms  the  salts 


ACETIC  ACID— ACETYLENE  3 

ACETIC  ACID  (Continued)— 

known  as  acetates,  most  of  which,  including  all  the  normal 
ones,  are  soluble  in  water. 

ACETIC  ANHYDRIDE  (C4H6O3)— A  colourless  mobile  liquid 
of  sp.  gr.  1-082  and  suffocating  odour,  which  boils  at  137°  C. 
It  may  be  chemically  regarded  as  derived  from  acetic  acid 
by  the  abstraction  of  a  molecule  of  water  from  two  mole- 
cules of  the  acid. 

2C2H402-H2O  =  C4H603. 

It  is  soluble  in  alcohol  and  ether,  and  resolved  by  water 
into  acetic  acid. 

ACETIC  ETHER— See  Ethyl  Acetate. 

ACETINE  (C2H3O2.C3H5(OH)2)— A  colourless,  thick  liquid  of 
sp.  gr.  i '22 12;  soluble  in  water,  alcohol,  and  ether;  used 
for  gelatinizing  smokeless  gunpowder  and  dynamite,  etc. 

ACETONE  (C3H6O  or  CH3OCH3)— A  mobile,  inflammable, 
colourless  liquid  of  agreeable  characteristic  odour,  obtained, 
amongst  other  methods,  by  the  dry  distillation  of  calcium 
acetate.  This  method  has  been  brought  to  a  high  degree 
of  efficiency,  but  the  reactions  involved  are  complex,  and 
there  are  many  by-products. 

To  produce  acetone  from  acetic  acid  the  latter  is  vapour- 
ized  and  passed  through  a  heated  vessel  containing  a 
catalyst  which  effects  its  decomposition,  as  expressed  above 
(under  Acetic  Acid).  The  products  are  passed  through  a 
hot  scrubber  containing  soda-ash,  by  which  the  unchanged 
acetic  acid  is  arrested,  thus  forming  sodium  acetate,  the 
acetone  passing  on  into  condensers,  from  which  it  is 
obtained  in  a  20  per  cent,  solution.  There  is  also  a  bio- 
chemical process  for  the  production  of  acetone  in  associa- 
tion with  butyl  alcohol  from  a  starchy  mass  under  aseptic 
conditions,  maize  being  the  material  chiefly  used  during 
the  war. 

It  is  largely  used  as  a  solvent  of  gun-cotton  and  celluloid 
bodies  ;  boils  at  56°  C.,  and  has  a  sp.  gr.  of  0-81  at  o°  C. 
Chemically,  it  belongs  to  a  series  of  bodies  named 
"  Ketones,"  and  it  is  said  to  be  present  in  urine  in  small 
quantity.  (See  Acetic  Acid  and  Ketones.) 

ACETYL  CHLORIDE  (C2H3C1O)— A  colourless  mobile  liquid 
which  boils  at  55°  C.,  and  has  a  suffocating  odour. 

ACETYLENE  (C2H2)— A  poisonous  hydrocarbon  gas  pro- 
duced from  calcium  carbide  by  allowing  water  to  drop  on 


4  ACETYLENE— ACIDS 

ACETYLENE  (Continued)— 

that  material  as  contained  in  a  suitable  generator,  which 
may  be  connected  with  a  gas-holder  in  which  the  gas  can 
be  stored  over  water — 

CaC2  +  2H20  =  Ca(OH)2  +  C2H2. 
It  is  soluble  in  water,  alcohol,  and  acetone. 

By  burning  acetylene  gas  in  conjunction  with  oxygen  in 
blow-pipe  form,  a  very  high  temperature  is  attained — 
higher,  indeed,  than  that  of  the  oxyhydrogen  flame — and  it 
can  be  effectively  used  as  a  means  for  cutting  through 
armour-plates  up  to  6  inches  in  thickness. 

ACETYLENE  TETRACHLORIDE  (CHC12.CHC12)— A  colour- 
less liquid  of  sp.  gr.  i'582,  used  as  a  solvent  for  greases 
and  waxes. 

ACIDS — By  the  word  "  acid  "  is  meant,  generally  speaking, 
something  that  is  sour.  Vinegar,  for  example,  is  acid  or 
sour  in  character,  and  contains  acetic  acid.  Acids  turn 
vegetable  blue  colours  into  red  colours,  tincture  of  litmus 
— a  vegetable  dye — being  ordinarily  employed  for  such 
testings. 

There  are  a  great  number  of  acids,  derived  from  various 
sources.  All  of  them  contain  replaceable  hydrogen,  so 
that  they  may  be  regarded  as  hydrogen  salts. 

Hydrochloric  Acid  is  a  combination  of  i  part  by  volume  of 
hydrogen  with  i  part  by  volume  of  chlorine,  and  is  repre- 
sented by  the  formula  HC1. 

Nitric  Acid  is  a  compound  of  i  part  hydrogen,  i  part 
nitrogen,  and  3  parts  oxygen  by  volume,  and  is  represented 
by  the  formula  HNO3. 

Sulphuric  Acid  is  compounded  of  2  parts  hydrogen,  i  part 
sulphur,  and  4  parts  oxygen — H2SO4. 

These  are  the  three  best-known  inorganic  acids,  and  they 
are  all  largely  used  in  commerce  and  manufacturing 
operations. 

Citric  Acid  (the  acid  of  citrons  and  lemons),  Acetic  Acid, 
Malic  Acid  (the  acid  of  apples),  Tartaric  Acid,  and  Oxalic 
Acid,  are  five  of  the  better-known  acids  from  organic 
sources. 

These  several  acids — all  of  which  are  soluble  in  water — 
by  combination  with  bases  form  the  corresponding  chlorides, 
nitrates,  sulphates,  citrates,  acetates,  malates,  tartrates, 
oxalates,  etc.,  as  illustrated  by  the  following  typical 
equations : 

2HC1       +       Na20       =       2NaCl       +       H2O. 

(Hydrochloric  Acid)       (Sodium  Oxide)  (Sodium  Chloride)  (Water) 


ACIDS  5 

ACIDS  (Continued)  — 

HN03       +       NaHO     -       NaNO3      +       H2O. 

(Nitric  Acid)  (Sodium  Hydroxide)       (Sodium  Nitrate)  (Water) 

H2SO4     +     Na2CO3     =     Na2SO4     +     H2O    +    CO2. 

(Sulphuric  (Sodium  (Sodium  (Water)  (Carbon 

Acid)  Carbonate)  Sulphate)  Dioxide) 

These  acids  and  some  of  their  compounds  are  described 
under  their  several  names. 

Acids  are  termed  monobasic,  dibasic,  tribasic,  and  tetra- 
basic,  according  to  the  number  of  hydrogen  atoms  con- 
tained in  them  being  replaceable  by  a  metal ;  thus,  acetic 
acid  is  monobasic,  sulphuric  acid  is  dibasic,  and  so 
forth. 

Organic  Acids,  like  the  inorganic  series,  may  be  generally 
described  as  substances  capable  of  yielding  salts  by  inter- 
action with  metallic  or  other  bases.  They  are  of  immense 
numbers  and  diverse  characters.  One  series  corresponds 
to  the  primary  alcohols  and  aldehydes  described  under 
these  several  headings,  and  is  known  as  the  acetic  or  "  fatty 
acids  "  series,  thus — 

Formic   acid   (CH2O2)    corresponds  with    Methyl  alcohol 

(CH3HO); 
Acetic    acid    (C2H.O2)    corresponds   with    Ethyl   alcohol 

(C2H5HO); 
Propionic  acid  (C3H6O2)  corresponds  with  Propyl  alcohol 

(C8H7HO) ;  and 

Butyric   acid    (C4H8O0)   corresponds  with   Butyl  alcohol 
(C.H.HO). 

It  will  be  seen  that  these  acids  rise  in  steps  of  CH2,  and 
they  are  formed  by  the  oxidation  of  their  corresponding 
alcohols  or  aldehydes.  Many  of  the  higher  members  of 
the  series  are  solid  bodies,  and  most  of  them  are  described 
under  their  individual  names. 

Fatty  acids  can  be  obtained  by  the  catalytic  oxidation  of 
petroleums.  (See  Petroleum.) 

A  second  group  of  acids  is  the  so-called  lactic  acid 
(monobasic)  series,  and  a  third  group  is  known  as  the 
oxalic  acid  (dibasic)  series.  Yet  another  group,  styled 
the  aromatic  acids,  are  analogous  to  the  fatty  acids.  The 
individual  members  of  these  various  groups  are  described 
under  their  respective  names,  so  far  as  they  are  included 
in  this  dictionary. 

The  chemical  relationships  between  the  members  of  the 
•    lactic  and  oxalic  series  of  acids  respectively,  are  shown  by 
the  following  typical  examples  : 


6  A  CIDS—A  CTINI  UM 

ACIDS  (Continued)  — 

Carbonic  Acid  CO       }^         Oxalic  Acid  C9O, 


Glycolic  Acid  C2H2O|O  Malonic  Acid  C3H2O2)O 

"2^  -"-2^ 

Lactic  Acid  C3H4O     \n  Succinic  Acid  C4H4O 
H 


The  phenols  and  cresols,  or  so-called  tar  acids,  while, 
having  weak  acid  characters,  stand  in  a  class  by  themselves 
and  to  some  extent  behave  like  alcohols. 

Hydrocyanic  acid  (HCN)  (a  member  of  the  cyanogen 
group  of  compounds)  constitutionally  resembles  hydrochloric 
acid,  the  radical  cyanogen  (CN)  behaving  like  chlorine  as  a 
halogen  in  this  respect  and  playing  the  part  of  an  element, 
so  to  say,  in  many  of  its  compounds. 

ACONITIC  ACID  (C6H6O6)—  A  crystallizable  substance  soluble 
in  water  and  found  naturally  in  Aconitum  napellus,  shave- 
grass,  and  cane-  juice.  It  is  tribasic  and  can  be  prepared 
by  heating  citric  acid  (C6H8O7),  thus  causing  the  loss  of  the 
elements  of  water. 


ACONITINE  (CgjH^NOn)—  A  white,  crystalline,  extremely 
poisonous  alkaloid  obtained  from  aconite  root,  which  melts 
at  195°  C.  and  is  soluble  in  alcohol  and  ether.  The  leaves 
of  Aconitum  napellus  (Monk's-hood)  contain  from  0*1  to  i  per 
cent,  of  the  alkaloid,  which  is  used  medicinally,  admixed 
with  chloroform  in  the  form  of  a  liniment,  to  relieve 
neuralgia,  etc. 

ACROLEIN  (C3H4O  or  CH2  :  CH.CHO)—  A  substance  of 
aldehydic  character  produced  by  the  oxidation  of  allyl- 
alcohol  (C3HgO),  and  by  the  distillation  of  fats.  It  is  a 
colourless,  inflammable,  and  poisonous  liquid  of  extremely 
pungent  odour,  having  a  violent  action  on  the  eyes.  It  has 
a  sp.  gr.  of  0-84  ;  boils  at  52°  C.  ;  is  soluble  in  water, 
alcohol,  and  ether.  It  yields  acrylic  acid  (C3H4O2)  by 
oxidation,  and  this  upon  fusion  with  alkali  breaks  up  into 
acetic  and  formic  acids. 

ACRYLIC  ACID—  See  Acrolein. 

ACTINISM  —  The  chemical  effects  of  light,  chiefly  exercised  by 
the  violet  rays. 

ACTINIUM  —  Name  of  a  radio-active  substance  resembling  and 
being  a  product  of  the  disintegration  of  thorium  ;  obtained 
from  uranium  minerals  (pitch-blende),  but  no  atomic  weight 


A  CT1NI UM—A  D  REN  A  LIN  7 

ACTINIUM  (Continued)— 

has  yet  been  assigned  to  it.  Aqueous  solutions  of  its  salts 
slowly  evolve  hydrogen  and  oxygen  in  the  proportions  in 
which  they  exist  in  water. 

1 '  ADAMANTINE  "—A  proprietary  brand  of  fire  and  alkali 
proof  material  for  use  in  sulphur,  pyrites,  zinc-blende,  and 
other  burners. 

ADDITIVE  COMPOUNDS — Are  those  formed,  as  it  were,  by 
mere  addition  of  elements  to  compounds  or  of  compounds 
to  compounds,  instead  of  by  substitution  or  replacement. 
For  example,  ethylene  (C2H4),an  unsaturated  hydrocarbon, 
combines  with  chlorine,  forming  ethylene  chloride  (C2H4C12), 
by  direct  addition,  thus  satisfying  two  spare  affinities  of 
the  carbon  atoms  in  the  ethylene. 

ADENINE  (C5H5N5) — An  alkaloidal  base  found  in  the  pancreas 
and  in  a  number  of  vegetable  growths,  which  has  also  been 
produced  synthetically. 

ADEPS  LAN.32  (Lanoline) — A  refined  wool  fat,  prepared  from 
"  suint,"  of  melting-point  about  40°  C.  (See  Suint.) 

ADHESION — The  property  of  holding  particles  together. 

ADHESIVES — Some  varieties  of  adhesives  are  made  from  the 
proteins  or  alkali -proteins  which  are  isolated  from  the 
residues  resulting  from  the  extraction  or  expression  of  oils 
from  seeds,  and  in  particular  hemp-seed  and  castor-beans. 
These  are  treated  with  suitable  bases,  such  as  the  alkaline 
earth  hydroxides,  or  magnesia,  and  with  an  alkali  salt 
(such  as  sodium  fluoride  or  arsenate),  which  will  react 
slowly  with  the  bases  and  form  alkali  hydroxide,  the  re- 
sulting product  being  then  mixed  with  dilute  alkali 
hydroxide  solution. 

Adhesives  are  also  made  from  seaweeds,  and  from  various 
starches  and  gelatinous  bodies,  such  as  gums  and  glues. 
(See  also  Mucilage.) 

ADIPIC  ACID  (C6H10O4)— A  member  of  the  oxalic  series  of 
acids  produced  by  the  action  of  nitric  acid  upon  oleic  acid 
and  other  fatty  acids.  It  is  a  solid  crystalline  body  soluble 
in  alcohol,  ether,  and  hot  water,  which  melts  at  153°  C. 

ADIPOCERE — Fatty  matter  which  is  found  in  dead  bodies 
buried  under  peculiar  circumstances. 

ADIPOSE  (substance) — Animal  oil  or  fat. 

ADEENALIN  (C9H13NO3)— A  nearly  white  crystalline  sub- 
stance prepared  from  the  suprarenal  glands  of  sheep  and 
cattle,  used  in  medicine.  It  melts  at  from  205°  to  212°  C., 


8  A  DRENA  UN- A  ER1A  L 

ADRENALIN  (Continued)— 

and  is  slightly  soluble  in  water  but  insoluble  in  alcohol, 
ether,  and  chloroform,  and  is  used  in  medicine. 

ADSORPTION — This  term,  in  its  most  general  sense,  implies 
the  unequal  distribution  of  a  substance  at  the  boundary 
between  two  heterogeneous  phases,  and  when  these  concern 
a  solid  and  a  gas  it  is  usually  referred  to  as  gas  adsorption. 
Practically,  it  means  the  removal  or  abstraction  of  a  con- 
stituent of  gases  or  liquids  by  certain  agents,  as,  for 
instance,  the  removal  of  iodine  from  a  solution  of  it  in 
potassium  iodide  by  means  of  charcoal,  or,  again,  the 
surface  action  illustrated  by  the  condensation  of  hydrogen 
gas  by  means  of  palladium  (see  Occlusion),  and  the  reten- 
tion of  the  dark  colouring  matter  of  crude  sugar  solutions, 
as  effected  by  charcoal  during  nitration  processes. 

The  adsorption  compounds,  as  those  of  charcoal  and 
caramel,  or  charcoal  and  litmus,  do  not  resemble  ordinary 
chemical  compounds  in  constancy  of  composition  and 
more  or  less  resistance  to  decomposition  by  physical 
agencies,  and  are  generally  formed  at  the  surfaces,  the 
quantity  being  proportional  to  the  active  surface. 

The  relative  adsorptive  powers  of  various  kinds  of 
charcoal  depend  not  merely  upon  their  respective  capacities 
to  absorb  gases,  but  also  to  retain  them  at  reduced  pres- 
sures. 

It  has  been  ascertained  that  adsorbents  can  be  prepared 
from  certain  colloidal  solutions,  and  silica  gel  prepared  from 
a  colloidal  solution  of  silicic  acid  is  stated  to  exhibit  a  power 
of  adsorption  equal  or  superior  to  that  of  animal  charcoal. 
It  can  be  prepared  from  silicate  of  sodium  by  the  action 
of  a  dilute  mineral  acid,  and  is  stable  in  the  air  even  at 
high  temperatures.  Sulphur  dioxide  at  a  concentration  of 
0'5  per  cent,  in  air,  and  with  a  time  contact  of  0-8  second, 
is  stated  to  be  adsorbed  to  the  extent  of  100  per  cent.,  and 
it  is  thought  in  America,  where  the  process  has  originated, 
that  this  new  material  will  prove  very  valuable  in  a  number 
of  industrial  operations  for  effecting  the  selective  separa- 
tion of  mixed  gases  and  the  saving  of  solvents.  (See  also 
Catalytic,  Carbon,  Enzymes,  and  Occlusion.) 

AERATION — Charging  of  liquids  with  gases.  So-called  soda- 
water  is  water  (with  or  without  addition  of  a  little  alkali) 
charged  with  carbon  dioxide  gas  under  pressure.  Water  can 
be  similarly  charged  with  air  or  oxygen  gas.  Many  natural 
sparkling  waters  are  more  or  less  charged  with  gases. 

AERIAL— Character  of  air. 


AEROLITES-AIR  (ATMOSPHERE)  9 

AEROLITES — Meteoric  stones  reaching  the  earth  through  its 
atmosphere. 

AETHER— See  Ether. 

AFFINITY— See  Chemical  Attraction. 

AGAR-AGAR — A  jelly-like  preparation,  soluble  in  water, 
made  from  certain  seaweeds  found  in  the  East — chiefly  of 
the  genus  Gelidium  (class  Rhodophyceae) — and  used  in 
bacteriological  work  as  a  nutrient  material  for  bacterial 
growths  ;  also  as  an  adhesive,  sizing  for  silk,  and  veneering 
wood.  (See  also  Seaweeds.) 

AGATE — An  anhydrous  crystalline  form  of  natural  silica 
(SiO2) — a  variegated  chalcedony  found  in  many  parts  of  the 
United  States  and  elsewhere. 

AIR  (ATMOSPHERE)— The  air  is  a  mixture  of  gases.  Many 
years  ago  it  was  found  that  animals  which  were  confined 
in  a  limited  amount  (volume)  of  air  died  after  a  short 
time.  Later,  it  was  ascertained  that,  in  breathing,  animals 
do  not  consume  (use  up)  all  of  the  air  which  is  inspired 
(breathed  in),  but  only  a  part  of  it,  and  that  part  is  now 
known  as  oxygen  ;  the  other  chief  part,  known  as  nitrogen, 
is  of  no  direct  use  for  sustaining  life. 

Air  is  substantially  a  mixture  of  oxygen  gas  (about  21 
parts)  and  nitrogen  gas  (about  79  parts).  It  really  contains 
small  quantities  of  other  gases,  also  varying  proportions  of 
moisture  (water)  in  consequence  of  the  evaporation  of  water 
from  the  land  and  water  surfaces  of  the  earth  which  is 
always  going  on.  For  any  given  temperature,  there  is  a 
maximum  amount  of  water  vapour  which  a  given  volume 
of  air  is  capable  of  taking  up  or  dissolving,  and  under  these 
conditions  it  is  saturated  with  moisture  at  that  particular 
temperature.  Instruments  which  have  been  devised  for 
determining  the  amount  of  moisture  contained  in  a  given 
volume  of  air  are  termed  hygrometers. 

A  cubic  metre  of  air  at  20°  C.  can  take  up  17 -157  grms. 
of  water,  but  at  o°  C.  it  can  only  hold  4-87  grms.,  so  that 
when  cooled,  the  excess  of  water  held  in  gaseous  solution  is 
deposited  as  mist,  dew,  rain,  hail,  or  snow. 

As  will  be  seen  under  the  description  of  oxygen,  that  gas 
can  be  prepared  in  the  laboratory  by  a  number  of  methods, 
but  it  is  a  natural  constituent  of  the  air,  the  composition  of 
which  is  materially  the  same  throughout  the  world. 

Animal  life  could  not  exist  if  this  oxygen  gas  were  not 
present  in  the  air,  and  the  most  interesting  point  is  that  the 
air  contains  such  a  much  larger  quantity  of  the  other  gas — 
nitrogen.  In  breathing — the  act  of  inspiration — the  oxygen 


io  AIR  (ATMOSPHERE) 

AIR  (ATMOSPHERE)  (Continued)— 

of  the  air  is  sucked  up  or  absorbed  in  the  lungs,  and  that 
reacting  upon  the  blood  forms  carbon  dioxide,  which  gas  is 
given  out  in  the  breath — the  act  of  respiration.  The  inert 
nitrogen  which  is  present  in  the  air  makes  the  oxygen  weak 
or  dilute  enough  to  enable  this  to  be  done,  as  oxygen  is  fatal 
to  human  life  when  continuously  breathed  in  its  pure  state. 

It  is  the  oxygen  of  the  air  that  also  sustains  the  com- 
bustion of  wood,  coal,  and  coke  in  fire-grates.  In  burning, 
the  carbon  of  which  coal  and  coke  are  largely  composed 
combines  or  enters  into  chemical  combination  with  the 
oxygen  of  the  air,  forming  carbon  dioxide,  and  gives  out 
heat  at  the  same  time.  Charcoal  is  a  form  of  carbon,  and 
if  a  piece  of  it  be  heated  to  redness  and  then  placed  in  a 
globe  or  glass  jar  containing  oxygen  gas,  it  becomes  much 
brighter  in  redness,  much  hotter,  and  gradually  disappears, 
being  burnt  up  (consumed)  and  thereby  converted  into 
carbon  dioxide  by  combining  with  the  oxygen. 

This  act  of  burning,  or  combustion  as  it  is  termed,  is 
essentially  dependent  upon  the  presence  of  oxygen.  If  an 
ordinary  night-light  be  lighted  and  placed  in  a  wide- 
mouthed  stoppered  bottle,  and  the  bottle  then  closed,  the 
night-light  will  go  on  burning  until  the  oxygen  contained  in 
the  air  present  in  the  bottle  has  been  used  up,  when  it  will 
go  out.  On  the  other  hand,  as  is  well  known,  it  will  go  on 
burning  in  the  open  air  until  it  is  all  consumed. 

The  air  always  contains  a  certain  quantity  of  carbon 
dioxide,  and  this  constituent  is  of  more  importance  than 
might  appear  without  careful  consideration,  bearing  in 
mind  how  essential  it  is  to  the  growth  and  development 
of  vegetable  life,  and  how  the  quantity  of  oxygen  contained 
in  the  air  is  maintained  by  way  of  compensation. 

It  has  been  estimated  that  the  amount  of  carbon  dioxide 
given  off  in  each  twenty-four  hours  through  the  lungs  of 
an  adult  human  being  is  that  which  results  from  the 
oxidation  of  between  7  and  n  ounces  of  carbon,  and  this 
necessitates  the  consumption  of  about  i|  pounds  of  oxygen 
gas  inhaled ;  and  if  now  we  multiply  this  quantity  by  the 
number  of  the  world's  inhabitants  (human  beings  and 
animals),  the  amount  of  oxygen  gas  thus  removed  from 
the  air  is  represented  by  an  astounding  figure.  The 
quantity,  indeed,  is  so  large  that,  unless  there  existed  some 
compensating  process,  life  would  in  course  of  time  become 
impossible  on  the  earth.  It  is  now  known  that  plant  life 
gives  back  to  the  atmosphere  the  oxygen  which  animal  life 
removes  from  it.  This  is  the  more  important  because, 


AIR  (ATMOSPHERE)— AIR-PUMP  n 

AIR  (ATMOSPHERE)  (Continued)— 

whereas  100,000  parts  of  air  ordinarily  contain  about  33 
parts  by  volume  of  carbon  dioxide,  larger  proportions  would 
foul  it  to  such  an  extent  as  to  produce  headache  and  other 
sickness,  while  the  presence  of  from  200  to  300  parts  is 
seriously  prejudicial  to  health.  Vegetable  life  absorbs  carbon 
dioxide  from  the  air,  as  also  from  decomposing  organic 
matter  in  the  soil,  and,  assimilating  the  carbon  in  its  tissues 
by  a  variety  of  chemical  processes,  gives  out  again  the 
oxygen  which  is  contained  in  it,  and  thus  maintains  the 
composition  of  the  air  practically  constant  and  universal. 
The  immensity  of  this  process  can  be  imagined  when  we 
reflect  upon  the  vast  extent  of  forestry  and  plant  life  which 
covers  the  surface  of  the  earth,  and  makes  us  realize  at  the 
same  time  the  great  importance  of  carbon  dioxide  as  a 
constituent  of  the  air  side  by  side  with  that  of  oxygen  and 
nitrogen,  its  other  chief  constituents.  (See  Vegetation.) 

The  air  of  towns  generally  contains  small  proportions 
of  ammonia,  sulphur  dioxide,  sulphuretted  hydrogen,  and 
organic  matters,  whilst  nitric  acid  is  produced  by  lightning 
flashes.  At  times,  ozone  in  small  proportion  also  forms  an 
aerial  constituent,  particularly  in  the  upper  layers,  whilst 
recent  investigations  have  revealed  the  presence,  as  normal 
constituents,  of  a  number  of  rare  gases  in  minute  quantities 
including  argon,  helium,  neon,  krypton,  and  xenon.  The 
relative  proportions  in  which  these  are  present  are  shown 
below : 

Argon  0*937  Part   m  100  air 

Helium  i      part    in       250,000  air 

Neon  i  to  2  parts  in       100,000  air 

Krypton  i      part    in    1,000,000  air 

Xenon  ...         ...       i       part    in  20,000,000  air 

The  weight  of  a  litre  (1,000  c.c.)  of  air  at  o°  C.  and 
760  mm.  of  pressure  is  1*2932  grms.  Its  constantly  vary- 
ing pressure  can  be  registered  at  the  earth's  surface  by 
means  of  the  barometer.  (See  Barometer.) 

AIR-PUMP — A  mechanical  appliance  provided  with  valves 
used  for  pumping  air  into  or  withdrawing  (exhausting)  it 
from  a  vessel.  The  hand  and  foot  pumps  used  for  pumping 
up  cycle  tyres  are  illustrative,  whilst  an  ordinary  syringe  is 
useful  for  many  purposes,  although  it  has  not  any  valves. 
Amongst  other  applications,  air-pumps  are  used  in  labora- 
tories in  association  with  desiccators  for  evaporating  opera- 
tions conducted  at  the  ordinary  temperature,  of  the 
atmosphere.  This  is  done  in  order  to  reduce  the  atmo- 


12  AIR-PUMP—ALBUMINS 

AIR-PUMP  (Continued)— 

spheric  pressure  and  thus  promote  the  evaporation  from 
the  containing  vessel,  and  at  the  same  time  to  remove  the 
aqueous  vapour  coming  from  the  substance  being  desiccated 
(dried)  in  the  partially  vacuous  space,  which  may  not 
already  have  been  absorbed  by  any  appliance  placed  therein 
for  that  purpose.  (For  illustration,  see  Desiccator  ;  see  also 
Pumps.) 

A  JO  WAN  OIL — From  the  seeds  of  Carum  ajowan,  which  yield 
about  3  to  4  per  cent,  of  sp.  gr.  from  0-900  to  0-930.  (See 
Thymol.) 

ALABASTER  —  A  native  form  of  fine-grained  gypsum  or 
calcium  sulphate  (CaSO4),  used  in  sculpture  and  for  orna- 
mental applications. 

ALBUMINOMETER  (Esbach's)  —  A  graduated  tube  about 
6  inches  long  and  J  inch  diameter,  graduated  so  that  each 
degree  indicates  o-i  per  cent,  of  albumin.  The  tube  is 
filled  to  a  given  mark  with  urine,  and  a  reagent  of  i  per 
cent,  picric  acid  and  a  2  per  cent,  solution  of  citric  acid  in 
distilled  water  is  then  added  up  to  another  mark.  This 
causes  the  precipitation  of  any  albumin  contained  in  the 
urine,  and  after  settlement  the  volume  is  read  off  by  the 
graduations  on  the  tube. 

ALBUMINS — Substances  constituting  one  of  the  principal 
divisions  of  the  larger  group  of  so-called  albuminoids  or 
"  proteins "  which  make  up  the  chief  part  of  the  flesh  of 
animal  organisms  and  are  contained  in  plants,  especially 
in  the  seeds.  They  are  uncrystallizable  nitrogenous  bodies 
of  complicated  composition  containing : 

Carbon  from  52-7  to  54-5  per  cent., 
Hydrogen  from  6*9  to  7-3  per  cent., 
Nitrogen  from  15-4  to  17*6  per  cent., 
Oxygen  from  20-9  to  23-5  per  cent.,  and 
Sulphur  from  o'8  to  5^0  per  cent. 

Some  are  more  or  less  soluble  in  water,  but  all  are 
soluble  in  dilute  alkaline  and  saline  solutions,  and  are 
precipitated  therefrom  by  alcohol.  When  their  solutions 
are  heated  they  become  coagulated. 

These  albuminoids  are  changed  by  mild  processes  of 
hydrolysis,  as  induced  by  the  action  of  dilute  acids  or  alkalies, 
as  also  by  the  enzymes  which  take  part  in  the  processes  of 
digestion,  into  so-called  albumoses  or  peptones,  and  when 
the  hydrolysis  is  carried  still  further,  a  variety  of  products 
result,  ultimately  terminating  with  a  number  of  substances 


A  LB  UMINS—A  LCOHOLS 


ALBUMINS  (Continued) — 

termed  amino-acids,  one  of  the  best  known  of  which  is 
tyrosine.     (See  Polypeptides.) 

The  putrefaction  of  albumins  gives  rise  to  the  production 
of  many  derivatives,  including  some  alkaloidal  substances 
called  ptomaines  or  toxines,  which  are  highly  poisonous,  and 
two  of  which  have  been  isolated — viz.,  "  putrescine  "  and 
"  cadaverine  " — and  their  chemical  constitutions  determined. 
Acted  upon  by  the  stomachic  secretions,  albuminoids  are 
converted  into  peptones,  which  are  soluble  in  water  and 
become  available  for  assimilation.  The  white  of  egg  is 
a  typical  albumin,  of  which  large  quantities  are  used  in 
France  for  the  clarification  of  wines.  (See  also  Blood 
Albumin,  Casein,  and  Proteins.) 

ALBUMOSES— See  Albumin  and  Proteins. 
ALCOBRONZE— See  Copper. 

ALCOHOL — Spirits  of  wine,  of  indefinite  alcoholic  strength. 
(See  also  Methylated  Spirit  and  Proof  Spirit.) 

ALCOHOL  TABLE,  SHOWING  THE  SPECIFIC  GRAVITIES  OF 
VARIOUS  STRENGTHS. 


Absolute  Alcohol 

Absolute  Alcohol 

per  Cent. 

S.G.  at  15-5°  C. 

per  Cent. 

S.G.  at  15-5°  C. 

by  Volume. 

by  Volume. 

I 

•9985 

55 

•9242 

5 

•9928 

60 

•9134 

10 

•9866 

65 

•9020 

J5 

•9810 

70      • 

•8899 

20 

•9760 

75 

•8772 

25 

•9709 

80 

'8637 

30 

•9654 

85 

•8494 

35 

'9591 

90 

•8337 

40 

•9518 

95 

•8i59 

45 

'9435 

100 

7939 

50 

'9343 

(See  Absolute  Alcohol  and  Fermentation.) 

ALCOHOLS— 

Ordinary  Alcohol  (Ethyl  Alcohol)  is  only  one  of  a  series 
of  homologous  alcohols  of  ascending  specific  gravities  and 
boiling-points,  the  lower  members  being  colourless  mobile 
liquids,  the  middle  ones  of  more  oily  character,  and  the 


14  ALCOHOLS 

ALCOHOLS  (Continued)— 

higher  ones  solid,  like  paraffin  in  appearance  and  without 
taste  or  odour.  Some  are  found  in  nature  in  combination 
with  organic  acids  in  essential  (ethereal)  oils  and  waxes. 

Methyl  Alcohol,  CH3OH  (or  CH4O),  is  contained  in 
combination  with  salicylic  acid  in  oil  of  wintergreen,  and 
is  found  among  the  products  of  the  distillation  of  wood. 
It  is  a  limpid,  colourless,  volatile  liquid  which  boils  at 
66°  C.,  has  a  sp.  gr.  of  0*8,  burns  with  a  non-luminous 
flame,  and  is  a  solvent  of  fats  and  oils.  It  is  soluble  in 
water,  and  is  used  commercially  in  making  spirit  varnishes, 
polishes,  and  for  "  methylating  "  spirits  of  wine.  Upon 
oxidation,  it  yields  formaldehyde  (CELO),  and  finally  formic 
acid  (CH202). 

Ethyl  Alcohol  (Absolute  Alcohol  or  Grain  Spirit) 
(C2H5OH  or  C2H6O)  is  a  limpid,  colourless,  volatile, 
inflammable  liquid  which  boils  at  78-3°  C.,  and  has  a  sp.  gr. 
of  079.  By  oxidation,  it  is  converted  into  acetaldehyde 
(C2H4O),  and  finally  acetic  acid  (C2H4O2).  It  is  the  pro- 
duct of  the  fermentation  of  sugar  (glucose),  and  the  intoxi- 
cating principle  of  wines,  beers,  and  spirits  (gin,  whisky, 
brandy,  and  rum).  (See  Wines.) 

Alcohol  is  prepared  commercially  from  the  starches  of 
cereals  or  potatoes  or  from  sugar  by  processes  of  fermenta- 
tion. The  starches  are  first  of  all  converted  into  maltose 
by  the  action  of  malt,  or  otherwise  saccharified,  the  extract 
or  "  wort "  being  then  subjected  to  fermentation  as  in 
brewing,  and  subsequently  distilled  in  order  to  obtain  the 
alcohol  thus  produced.  This  process  of  fermentation  has 
been  applied  to  the  waste  sulphite  liquors  resulting  from 
pulp  production.  (See  Paper.) 

In  the  Philippine  Islands,  alcohol  is  made  on  a  com- 
mercial scale  from  the  sap  of  the  Nipa  palm,  although  the 
production  of  sugar  from  that  source  is  at  present  only  in 
the  experimental  stage. 

Alcohol  is  also  made  to  some  extent  from  wood-waste 
and  sawdust  by  conversion  of  their  cellulose  contents  into 
saccharoids  and  subsequent  fermentation.  Pine- wood  saw- 
dust is  stated  to  give  the  best  result,  yielding  not  less  than 
12  per  cent,  calculated  on  the  dry  sawdust. 

The  "  Amylo  "  process  carried  on  near  Lille  depends 
upon  the  use  of  certain  moulds,  such  as  the  Asptrgttlac&f, 
for  saccharifying  starch  instead  of  malt — the  Rhizopus 
delemar  or  Mucor  boulard  being  now  almost  exclusively 
employed — thus  avoiding  the  formation  of  the  unfer- 
mentable  dextrins  which  result  to  some  extent  when  malt 


ALCOHOLS  15 

ALCOHOLS  (Continued)— 

is  used.  The  yeast  used  for  fermenting  the  material  thus 
prepared  exercises  its  optimum  effect  at  38°  C.,  and  the 
process,  which  takes  in  all,  four  days  to  complete,  yields  up 
to  97-5  per  cent,  of  the  alcohol  theoretically  obtainable. 

Attempts  have  also  been  made  to  produce  ethylic  alcohol 
from  the  ethylene  contained  in  coke-oven  gases  by  absorb- 
ing it  in  95  "per  cent,  sulphuric  acid  and  hydrolizing  the 
ethyl  sulphate  thus  produced  by  dilution  of  the  acid  mixture 
with  water  or  steaming,  thus  producing  alcohol,  which  is 
recovered  by  distillation  and  regenerating  the  sulphuric 
acid.  Of  course  the  gas,  prior  to  this  procedure,  is  freed 
from  tar,  ammonia,  naphthalene,  benzol,  sulphuretted 
hydrogen,  the  higher  defines,  and  water  vapour  in  the  order 
as  here  given.  It  is  on  record  that  1*6  gallons  of  alcohol 
can  be  thus  obtained  from  each  ton  of  the  particular 
Durham  coal  employed. 

Alcohol  is  soluble  in  water,  and  is  largely  used  as  a 
solvent,  in  the  manufacture  of  explosives,  chemicals, 
perfumes,  lacquers,  pharmaceutical  extracts  and  tinctures ; 
also  as  a  fuel,  in  the  compounding  of  drinks,  and  for  pre- 
serving anatomical  specimens. 

Although  its  calorific  value  is  not  much  more  than  one 
half  that  of  petrol,  its  efficiency  is  much  greater  owing  to 
its  relatively  greater  combustion.  It  can  be  compressed 
to  a  greater  extent,  and  this  property  of  high-ignition 
temperature  under  compression  is  not  materially  altered  by 
admixture  with  20  per  cent,  benzene  or  petrol.  Such  a 
mixture  readily  starts  in  the  cold  and  runs  smoothly ;  so 
that  if  alcohol  could  be  manufactured  sufficiently  cheap  it 
would  become  a  serious  competitor  with  petrol  as  a  motor 
fuel. 

Propyl  Alcohol  (C3H7OH  or  C3H8O)  is  a  spirituous 
colourless  liquid  which  can  be  obtained  from  fusel  oil.  It 
boils  at  97°  C.,  and  has  a  sp.  gr.  of  0-806.  By  oxidation 
it  yields  propylaldehyde  (C3H6O),  and  finally  propionic  acid 
(C3H602). 

Butyl  Alcohol  (C4H9OH  or  C4H10O),  a  limpid,  colour- 
less liquid  which  boils  at  117°  C.,  has  a  sp.  gr.  of  0-824, 
and  by  oxidation  yields  butyric  acid  (C4H8O2).  It  is  used 
to  some  extent  in  making  fruit  essences. 

There  are  further  members  of  this  class  of  so-called 
monohydric  or  aliphatic  alcohols,  including  amyl  alcohol 
(C^OH),  hexyl  alcohol  (C5H13OH),  and  heptyl  alcohol 
(CrH15OH) ;  in  addition,  there  are  other  series  of  alcohols 


i6  ALCOHOLS— ALDEHYDES 

ALCOHOLS  (Continued}  - 

— viz.,  the  dihydric  alcohols    or  glycols,  and  the  trihydric 
alcohols,  of  which  ordinary  glycerine  is  a  member. 

The  glycols  include  ethyl  glycol  (C2H6O2  or  C2H4,2HO), 
propyl  glycol  (C3H8O2  or  C3H6,2HO),  and  butyl  glycol 
(C4H10O2  or  C4H8,2HO),  and  so  forth.  They  are  mostly 
thickish  liquids  of  somewhat  sweet  taste,  readily  soluble 
in  water  and  alcohol. 

Of  the  trihydric  alcohols,  or  glycerines,  glycerol  or 
ordinary  glycerine  is  a  member  and  illustrative,  its  formula 
being  C3H8O3  or  C3H5,3HO.  (See  Glycerine.) 

The  commercial  article  known  as  Alcohol  Solidified  is 
really  a  mixture  of  alcohol,  or  alcohol  and  methylated 
spirit,  with  soap.  One  formula  is — alcohol,  60  parts  ; 
methylated  spirit,  40  parts ;  and  sodium  stearate,  about 
3  parts. 

ALDEHYDES  constitute  a  series  of  organic  bodies  (mostly 
liquids)  related  to  the  alcohols  and  the  ethers,  and  are 
formed  as  first  products  of  the  oxidation  of  the  alcohols 
by  the  elimination  of  two  atoms  of  hydrogen  therefrom 
(C2H5HO  less  H2  =  C2H4O).  This  relationship  is  illus- 
trated by  the  following  equation  in  the  case  of  ethyl 
alcohol,  C2H5HO+O  =  C2H4O  +  H2O.  By  further  oxi- 
dation, the  aldehydes  so  produced  are  converted  into  a 
corresponding  series  of  acids ;  thus  ethyl  aldehyde  becomes 
oxidized  to  acetic  acid,  C2H4O  +  O  =  C2H4O2. 

The  lower  members  of  the  aldehydes  are  neutral  volatile 
liquids  of  characteristic  odour,  soluble  in  water,  with 
lower  boiling-points  than  those  of  the  corresponding 
alcohols. 

These  aldehydes  are  easily  reconverted  into  their  cor- 
responding alcohols  by  the  action  of  nascent  hydrogen  ; 
thus  the  ethyl  or  acetic  aldehyde  is  changed  back  to  ethyl 
alcohol,  as  shown  in  the  equation,  C2H4O  +  H2  =  C2H5HO. 

This  can  be  realized,  for  example,  by  passing  its  vapours 
with  hydrogen  gas  over  finely  divided  copper  or  nickel  at 
120°  to  300°  C.  With  copper  the  yield  is  87-6  per  cent,  at 
200°  C. 

It  is  the  Ethyl  Aldehyde  (CH3CHO)  that  is  commonly 
known  as  acetaldehyde  or  aldehyde,  and  it  is  ordinarily 
prepared  by  the  oxidation  of  ethyl  alcohol  by  means  of 
potassium  dichromate  or  manganese  dioxide  and  sulphuric 
acid.  It  is  a  colourless,  mobile,  inflammable,  volatile 
fluid  of  a  peculiar  pungent  odour,  boiling  at  22°  C.,  and 
of  sp.  gr.  0-801,  miscible  with  water,  alcohol,  and  ether, 


ALDEHYDES— ALIZARIN  17 

ALDEHYDES  (Continued) — 

and  possesses  strong  reducing  properties  (see  Reducing 
Agents).  Apart  from  its  chemical  applications,  it  finds 
use  as  a  solvent  and  as  an  antiseptic  inhalant  in  cases 
of  nasal  catarrh  and  ozaena.  It  is  otherwise  known  as 
"ethanal." 

Methyl  Aldehyde  (CH2O),  the  next  lower  member  of  the 
series,  is,  in  its  normal  state,  an  exception  to  the  rule 
above  stated,  being  a  gas,  and  is  produced  as  described 
under  Formaldehyde,  which  is  the  common  name  for  it  : 
CH3HO  (methyl  alcohol)  +  O  =  CH2O  +  H2O.  It  is 
otherwise  known  as  "  methanal."  (See  Formaldehyde 
and  Paraform.) 

ALEMBROTH  (SALT  OF)— A  crystalline  compound  of  mercu- 
ric chloride  and  ammonium  chloride  (2NH4Cl,HgCl2,H2O), 
prepared  by  mixing  solutions  of  the  two  salts  in  suitable 
proportions. 

ALG^E — An  order  of  flowerless  plants,  including  the  sea- 
weeds (fucus)  and  the  fresh-water  confervas.  (See  Sea- 
weeds.) 

ALGIN — A  gelatinous  (albuminous)  material,  being  a  sodium 
salt  of  alginic  acid,  obtained  from  seaweeds,  which  finds 
some  industrial  applications,  and  can  be  used  as  a  food. 
It  is  obtained  by  soaking  the  marine  algae  for  twenty-four 
hours  in  a  i  per  cent,  solution  of  sodium  carbonate,  filtering 
the  viscous  liquor  through  cloth,  and  precipitating  it  there- 
from by  dilute  sulphuric  acid,  washing,  and  drying. 

The  compounds  of  algin  give  very  viscous  solutions,  and 
are  valuable  as  sizings  for  textiles  and  paper,  as  thickenings 
for  printing  colours,  and  as  proofings  for  interior  walls  and 
ceilings. 

The  sodium  compound  is  soluble  in  water,  and  a  5  per 
cent,  solution  is  so  viscous  that  it  can  hardly  be  poured  out 
from  its  containing  vessel. 

The  heavy  metallic  compounds  are  insoluble  in  water, 
but  some  are  soluble  in  ammonia,  and  these  solutions  are 
used  as  waterproofing  materials  for  textiles. 

ALIZARIN  (C14H8O4  or  C6H4(CO)2C6H2(OH)2)— An  im- 
portant colouring  matter,  prepared  from  the  roots  of  the 
madder  plant  (grown  largely  in  Alsatia),  and  now  made 
on  an  extensive  scale  by  a  synthetic  process  from 
anthracene.  It  is  contained  in  the  red  dye  of  madder 
root  (Rulia  tinctovum)  in  the  form  of  a  glucoside. 


18 


ALIZARIN— ALKALI  TRADE 


ALIZARIN  (Continued)— 

crystallizes  in  fine  red  prisms  and  needles,  which  melt  at 
289°  C ;  is  sublimable,  and  soluble  in  alcohol  and  ether, 
but  only  to  a  small  extent  in  water.  With  metallic  oxides 
it  gives  very  fine  "  lakes ''  of  varying  hues,  and  is  used  in 
making  dyestuffs. 

ALKALI  METALS— See  Bases. 
ALKALI  TRADE- 
CHART   SHOWING   THE    PROCESSES    EMPLOYED. 

and  Soda  Nitre  (NaNO3) 


From  Iron  Pyrites 
(Sulphide  of  Iron,  FeS) 


there  are  produced: 


Burnt  Ore  and 

from  which  are  extracted 


Sulphuric  Acid,  which  is  used 


Iron     Copper     Silver  and  Gold. 


to  act  upon 

Common  Salt  (NaCl) 

making 


I 

to  act  upon 

Magnesia  to  make 

Epsom  Salts 

(MgSOJ. 


Hydrochloric  Acid  (HC1), 
which  is  used  with  Man- 
ganese Ores  to  make 


and 


Sulphate  of  Sodium  (Na2SO4), 
from  which  is  produced 


| 

I 

1 

Chlorine  Gas, 

M  a  n  g  an- 

Carbonate      of 

and 

which   is 

ese    Chlor- 

Soda(Na2CO3), 

'  '  Alkali  waste,  ' 

used  to 

ide    (MnCl2) 

from         which 

from     which 

make 

(from  which 

also       Caustic 

the    Sulphur 

the  Mangan- 

Soda   (NaHO^ 

is  recovered. 

ese     is     re- 

is made. 

covered     as 

Oxide      and 

used       over 

again)     and 

Calcium 

Chloride 

(CaCy. 

Bleaching  Powder 
(Chloride  of  Lime). 

Potassium 
Chlorate 

(KClOg). 

ALKALI  TRADE— ALKANET  19 

ALKALI  TEADE  (Continued)— 

In  1869  it  was  estimated  that  the  total  quantity  of  salt 
decomposed  in  Great  Britain  for  the  production  of  soda 
was  326,000  tons. 

ALKALI  WASTE— The  residual  matter  or  by-product  from  the 
manufacture  of  sodium  carbonate  by  the  old  (Leblanc) 
process.  For  every  ton  of  soda  ash  produced  there  are  from 
one  and  a  half  to  two  tons  of  waste.  Many  processes 
have  been  devised  for  the  extraction  or  recovery  of  the 
sulphur  it  contains  in  combination  with  calcium — viz.,  15 
to  20  per  cent. — and  of  these  the  most  important  is  the 
"  Chance "  process,  which,  however,  is  applicable  only 
to  recently  made  waste  as  distinct  from  the  old  accumu- 
lated masses  lying  in  manufacturing  areas,  and  which 
rapidly  undergoes  chemical  changes  by  atmospheric  action. 
(See  Sodium  and  Sulphur.) 

ALKALIES— See  Bases. 

ALKALINE  EAETH  METALS— See  Bases. 

ALKALOIDS — A  nitrogenous  class  of  organic  substances 
(bases),  viewed  by  some  as  built  up  or  derived  from 
amino-acids.  They  are  basic  or  alkaline  in  character,  and 
may  be  regarded  on  the  whole  as  compound  ammonia 
bodies,  resembling  ammonia,  as  many  of  them  do,  in 
forming  definite  or  crystalline  salts  with  acids,  and  in  other 
respects.  They  are  individually  described  under  their 
several  names. 

The  vegeto-alkaloids  occurring  in  plants,  in  contra- 
distinction to  those  derived  from  animal  sources  (such  as 
cadaverine),  constitute  an  important  group  of  compounds 
by  reason  of  their  physiological  properties,  and  are  the 
active  principles  of  many  drugs.  As  they  exist  in  plants 
they  are,  for  the  most  part,  in  combination  with  acids  such 
as  citric,  malic,  tannic,  and  quinic  acids,  and  comprise 
quinine  and  the  other  associated  alkaloids  (see  Opium), 
atropine,  berberine,  brucine,  codeine,  coniine,  hyoscya- 
mine,  morphine,  nicotine,  papaverine,  pilocarpine,  solanine, 
strychnine,  etc.  As  a  class  they  are  bitter  compounds  of 
poisonous  character,  and  are  usually  extracted  from  the 
plant  tissues  containing  them  by  infusion  with  acidified 
water.  (See  also  Amines.) 

ALKANET — An  ancient  dyestuff  in  the  form  of  a  dark  red 
amorphous  powder,  prepared  from  the  roots  and  leaves  of 
the  shrub  Lawsonia  inermis.  It  exhibits  a  green  iridescence, 


20  ALKANET— ALLOYS 

ALKANET  (Continued)— 

and  is  used  in  the  East  for  dyeing  the  nails,  teeth,  and  hair, 
as  also  garments. 

ALKYLENES— The  divalent  residues  (CnH2n),  such  as  the 
defines. 

ALKYLS — The  monovalent  groupings,  such  as  methyl  and 
ethyl,  which  form  the  radicles  of  the  monovalent  alcohols. 

ALLANITE — A  natural  complex  silicate.     (See  Lanthanum.) 
ALLOPEANE — A  mineral  hydrated  aluminium  silicate. 

ALLOTROPY — The  property  of  assuming  various  distinct 
forms.  Oxygen  and  ozone,  for  example,  are  allotropic 
forms  of  the  same  substance.  Again,  carbon  is  known 
in  the  forms  of  the  diamond,  graphite,  and  charcoal. 
Sulphur  and  phosphorus  are  also  known  in  several  distinct 
forms.  It  has  been  conjectured  that  allotropy  is  to  be 
attributed  to  the  varying  number  of  atoms  contained  in 
the  molecules  of  the  various  substances  capable  of  assum- 
ing allotropic  forms. 

ALLOXAN  (C4H2N2O4) — A  derivative  of  uric  acid,  which 
yields  urea  by  the  action  of  barium  hydroxide. 

ALLOYS  —  Many  metals  when  melted  together  have  the  pro- 
perty of  combining  with  each  other  to  form  either  mixtures 
or  definite  compounds  called  alloys,  a  number  of  which  are 
very  useful  in  the  arts  and  manufactures.  At  least  some  of 
these  mixtures  may  be  regarded  as  solutions  of  definite  com- 
pounds in  an  excess  of  one  of  the  metals  employed,  and 
may,  therefore,  be  considered  as  solidified  solutions.  In 
this  way,  the  metals  aluminium,  zinc,  iron,  tin,  copper,  and 
lead  are  largely  used,  and  sometimes  mercury,  silver,  gold, 
and  platinum. 

So-called  German  silver  is  a  mixture  of  copper,  zinc,  and 
nickel;  and  brass  consists  of  about  2  parts  copper  and 

1  part  zinc. 

The  British  gold  coin  consists  of  pure  gold  22  parts,  and 

2  parts  alloy  of  silver  and  copper,  and,  until  recently,  silver 
coins  consisted  of  92^  parts  silver  and  yj  parts  copper. 

Descriptions  of  various  alloys  will  be  found  under  the 
headings  of  the  metals  used  in  compounding  them,  and  some 
of  the  better-known  ones  are  shown  in  tabulated  form  on 
the  opposite  page. 

Some  alloys  can  be  obtained  in  crystalline  forms  in 
which  the  combined  metals  are  associated  in  atomic  pro- 
portions. 


ALLOYS 


21 


ALLOYS  (Continued)— 

An  alloy  of  85  per  cent,  lead  and  15  per  cent,  magnesium 
when  exposed  to  moist  air  undergoes  rapid  oxidation, 
swelling  up  and  falling  to  a  black  powder  in  course  of  a  few 
hours,  the  interactions  being  expressed  as  follows  : 

(a)  Mg  +0  +  H2O  =  Mg02H2. 
(b\  2Pb  +  O  +  H2O=PboO9H2. 

\     /  2  222 

This  alloy  decomposes  water,  liberating  hydrogen,  and 
particularly  so  wrhen  the  proportion  of  magnesium  is 
increased  to  30  per  cent. 


a 

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Muntz  metal 



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Yellow  brass 

— 

66 

33 

— 

— 

— 

— 

— 

Britannia  metal  (a) 

— 

3 

140 

9 

— 

— 

— 

»           it       (&)••• 

— 

4 

— 

84 

10 

— 

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2 

Bell  metal  

— 

80 

20 

— 

— 

— 

— 

Bronze  (for  statues) 

— 

91-4 

5*53 

1-7 

— 

— 

r37 

— 

,,        (for  cannon) 

— 

90*0 

lO'O 

— 

— 

— 

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German  silver 

— 

50 

25 

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— 

25 

— 

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Type  metal 

— 

5 

20 

75 

— 

Stereotype  metal  ... 

— 

— 

— 

3 

18 

— 

112 

— 

Pewter 

— 

— 

— 

4 

— 

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— 

Wood's  fusible  metal 

I 

— 

— 

i 

— 

— 

2 

4 

Aluminium  is  extensively  used  in  making  a  number  of 
alloys  with  copper,  of  which  magnolium  in  several  varieties 
contains  from  10  to  30  per  cent,  of  magnesium  also.  It 
is  silver-white,  strong,  ductile,  and  easily  cast,  having  a 
sp.  gr.  of  from  2  to  2'5.  When  10  per  cent,  magnesium  is 
present,  the  alloy  has  a  melting-point  of  from  650°  to  700°  C. 

Alloys  of  aluminium  and  magnesium  of  the  compositions 
Al3Mg2  and  Al2Mg3  have  been  described,  and  other  mag- 
nesium alloys  adapted  to  special  applications  are  made 
containing  small  percentages  of  manganese,  nickel,  lead, 
tin,  and  iron.  Evidence  has  also  been  forthcoming  of  the 
existence  of  definite  alloys  of  copper  with  zinc  and  tin 
respectively  having  the  formulae  CuZn3  and  Cu3Sn. 

Soldering  consists  in  fusing  together  the  surfaces  of  the 


22  ALLOYS—ALUMINIUM 

ALLOYS  (Continued)— 

same  or  different  metals  by  means  of  an  interposed  alloy 
which  must  be  more  fusible  than  the  two  metals  to  be 
joined,  and  have  an  affinity  for  both  of  them.  (See  also 
Ferro- Alloys.) 

ALLSPICE  OIL  (oil  of  pimenta) — A  colourless  or  somewhat 
yellow  oil,  distilled  from  the  fruit  of  Pimenta  officinalis,  which 
darkens  and  thickens  upon  exposure  to  the  air,  and  has  a 
clove-like  odour.  It  has  a  sp.  gr.  of  from  1*02  to  1*05, 
refractive  index  about  1*53,  is  soluble  in  alcohol  and  ether, 
and  is  chiefly  used  for  flavouring. 

ALMOND  OIL — Bitter  almond  oil  is  extracted  by  maceration 
and  distillation  from  the  ripe  seeds  of  Amygdalus  communis, 
which  is  cultivated  in  Italy,  Spain,  and  the  south  of  France, 
thus  yielding  about  40  per  cent,  of  yellowish  oil  of  sp.  gr. 
1-045  to  1*070,  with  refractive  index  of  1-54.  It  is  soluble 
in  alcohol  and  ether,  and  is  used  for  flavouring  purposes. 
Its  fragrant  odour  is  due  to  benzaldehyde  (C7H6O),  which 
is  not  contained  in  the  original  oil,  but  is  produced  during 
the  maceration  by  the  action  of  the  enzyme  named  emulsin 
on  the  amygdalin  contained  in  the  fruit.  (See  Amygdalin.) 
Sweet  almond  oil  is  obtained  by  expression  of  the  same 
seeds.  It  has  a  yellowish  colour,  is  aromatic,  has  a  sp.  gr. 
of  0-915  to  0*920,  consists  mainly  of  olein,  and  is  used  in 
perfumery  and  as  a  delicate  lubricant. 

ALOES  (bitter  aloes) — The  inspissated  juice  of  various  species 
of  the  aloe,  containing  aloin  and  used  in  medicine. 

Barbadoes  aloes  comes  from  the  leaves  of  Aloes  vulgaris, 
and  is  a  dark-coloured,  resin-like  substance ;  Cape  aloes, 
from  A  loe  ferox,  A .  africana,  and  A .  spicata,  is  used  both  in 
medicine  and  dyeing. 

ALOIN  (C17H18O7) — A  yellow  crystalline  substance  extracted 
from  Barbadoes  aloes,  little  soluble  in  water  and  alcohol 
but  soluble  in  formamide  and  alkalies.  Used  in  medicine. 

ALOXITE  (aluminium  oxide,  A12O3) — Prepared  by  fusion  of 
bauxite  and  sold  as  an  abrasive. 

ALUMINIUM  (Al)  (atomic  weight,  27 ;  sp.  gr.  2-58 ;  melting- 
point,  658  7°  C.) — Aluminium  is  found  very  abundantly  in 
nature  in  a  state  of  combination,  but  not  in  the  metallic 
state.  Combined  with  oxygen  as  alumina  (A12O3),  it  forms 
the  substance  of  the  precious  stones  known  as  the  sapphire 
and  ruby,  both  of  which  are  now  produced  commercially  by 
the  fusion  of  pure  alumina  in  a  specially  constructed  electric 


ALUMINIUM  23 

ALUMINIUM  (Continued)— 

furnace,  and  are  as  good  in  all  respects  as  the  natural  gems, 
with  which  they  are  identical  in  composition  and  properties. 

In  combination  with  silica,  aluminium  exists  as  clay,  and 
in  another  form  of  combination  with  iron  oxide,  it  is  found  in 
the  mineral  known  as  bauxite  (A12O3,H2O),  from  which  it  is 
chiefly  manufactured  by  an  electrical  process.  Alumina 
prepared  from  bauxite  and  dissolved  in  fused  cryolite  (a 
double  fluoride  of  aluminium  and  sodium)  is  subjected  to 
electrolysis  in  iron  pots  lined  with  carbon,  carbon  rods  being 
used  to  carry  the  current,  the  power  used  for  generating  the 
electric  current  (by  dynamos)  being  that  of  falling  waters 
as  utilized  at  Niagara,  the  falls  of  the  Rhine  at  Schaff- 
hausen,  and  Kinlochleven  in  Argyllshire.  In  this  way,  the 
aluminium  oxide  is  decomposed,  the  melted  metal  collect- 
ing at  the  bottom  of  the  pots  and  oxygen  being  liberated  at 
the  carbon  poles. 

The  total  output  of  aluminium  in  the  year  1909  was 
estimated  at  30,000  tons. 

The  metal  is  extremely  light,  being  about  one-third  the 
weight  of  iron,  and  is  of  the  colour  of  tin.  It  is  very 
malleable,  ductile,  does  not  tarnish  when  exposed  to  the 
air,  is  a  good  conductor  of  electricity,  and  is  extensively 
used  in  the  construction  of  many  articles  both  for  manu- 
facturing and  household  employment.  Aluminium  powder 
mixed  with  oil  is  also  used  as  a  paint  for  iron  exposed 
to  the  air. 

When  combined  with  copper,  it  makes  an  alloy  known 
as  aluminium  bronze,  which  makes  good  castings.  This  bronze 
is  manufactured  by  heating  a  mixture  of  alumina  in  the 
form  of  corundum  with  charcoal  and  granulated  copper  in 
an  electric  furnace,  in  which  process  the  carbon  is  burned 
out  of  the  mixture  by  the  oxygen  of  the  alumina  (A1^O3), 
and  the  copper  combines  with  the  metallic  aluminium, 
forming  the  alloy.  The  so-called  "true  bronzes"  contain 
from  3  to  5  per  cent,  aluminium. 

An  alloy  of  85  per  cent,  aluminium,  12-5  per  cent,  zinc, 
and  2-5  per  cent,  copper  has  proved  very  successful  for 
general  castings,  crank  cases,  pump-bodies,  carburettors, 
etc.  Aluminium  has  been  used  in  the  construction  of 
zeppelins,  and  alloyed  with  various  other  metals  it  can  be 
usefully  employed  where  lightness  combined  with  strength 
are  desirable  qualities.  In  the  form  of  powder  it  finds  use 
as  an  ingredient  of  certain  explosives  (see  Ammonal)  and 
in  the  "  thermit  process,"  while  it  is  also  largely  employed 
in  the  metallurgy  of  other  metals. 


24  ALUMINIUM  COMPOUNDS 

ALUMINIUM  (Continued)— 

Corundum,  a  nearly  pure  natural  oxide  of  aluminium, 
occurs  in  crystallized  form,  hard  enough  to  cut  glass  ;  it  is 
now  made  by  an  electric  process  on  a  considerable  scale, 
and  is  largely  used  for  polishing  purposes. 

Aluminium  is  the  essential  constituent  of  the  salts  or 
compounds  known  as  alums,  which  have  important  applica- 
tions in  the  industries  of  dyeing  and  calico  printing. 

Aluminium  Oxide  or  Alumina  (A12O3)  is  used  as  a 
mordant  in  dyeing  and  calico  printing  owing  to  its  property 
of  forming  insoluble  compounds  known  as  "lakes"  with 
vegetable  colours,  thus  fixing  them  in  the  tissues  under- 
going treatment  and  making  them  washable  or  "  fast."  In 
hydrated  form  it  can  be  prepared  by  adding  ammonia  to 
a  solution  of  alum,  as  a  white  precipitate  (A12O3.3H2O), 
which  can  be  rendered  anhydrous  by  drying  and  heating. 

A  dry  process  for  the  preparation  of  alumina  involves 
furnacing  bauxite  with  soda,  and  subsequent  extraction  of 
the  aluminate  by  leaching  with  water,  and  a  wet  process  in 
which  the  mineral  is  first  heated  under  pressure  with  a 
solution  of  caustic  soda.  From  these  solutions  the  alumina 
is  obtained  by  two  several  methods.  In  the  one,  carbon 
dioxide  gas  is  blown  into  the  solution,  thus  precipitating 
the  A12O3,  and,  in  the  other,  the  solution,  after  dilution,  is 
stirred  with  a  small  quantity  of  hydrated  alumina,  in 
which  case  a  large  proportion  of  the  alumina  in  solution 
is  precipitated,  leaving  a  liquid  which,  after  concentration, 
is  used  for  attacking  a  fresh  quantity  of  bauxite. 

In  another  process,  known  as  the  "  Serpek,"  or  "  nitride," 
bauxite,  carbon  (coal),  and  nitrogen  are  made  to  react  at  a 
high  temperature  (1,700°  to  1,800°  C.),  and  the  aluminium 
nitride  thus  produced  yields  sodium  aluminate  upon  treat- 
ment with  sodium  hydroxide,  ammonia  being  incidentally 
obtained  as  a  by-product.  From  this,  pure  alumina  can 
be  readily  produced  ready  for  the  application  of  the 
electrical  process  for  production  of  the  metal. 

A  process  has  recently  been  used  in  Norway  for  pro- 
ducing alumina  from  this  mineral  by  leaching  with  a 
30  per  cent,  nitric  acid  solution,  which  dissolves  the 
aluminium,  calcium,  and  part  of  the  iron  contents,  leaving 
the  silica  and  the  rest  of  the  iron  undissolved.  The  iron  is 
then  removed,  the  solution  evaporated  to  dryness,  and  the 
residue  heated  to  such  an  extent  that  the  aluminium  salt 
only  is  decomposed.  The  nitrogen  oxides  driven  off  in  this 
operation  are  recovered  as  nitric  acid,  and  the  alumina  is 


ALUMINIUM  COMPOUNDS  25 

ALUMINIUM  (Continued)— 

employed  for  the  manufacture  of  the  metal  and  its  various 
compounds. 

Aluminium  Chloride  (A1C13)  is  a  white  volatile  solid  sub- 
stance produced  by  heating  powdered  metallic  aluminium, 
or  a  mixture  of  alumina  and  charcoal,  in  a  current  of 
chlorine.  It  was  at  one  time  used  for  the  manufacture  of 
the  metal.  The  hydrated  salt  is  A1C13.6H2O,  and  both  are 
soluble  in  water  and  alcohol. 


Aluminium  Sulphate  (Al^SO^glSHgO)  constitutes  the 
natural  minerals  aluminite  and  hair-salt,  and  large  quantities 
are  manufactured  by  dissolving  the  mineral  bauxite  in 
sulphuric  acid  and  purifying  the  product  from  associated 
iron  impurities  which  would  interfere  with  its  applications 
in  the  dyeing  and  other  industries.  It  is  soluble  in 
water. 

Aluminium  Nitrate  (A1(NO3)3),  in  anhydrous  and  hydrated 
forms,  is  a  white  crystalline  body,  soluble  in  water,  used 
in  the  textile  and  leather  industries. 

Alums  are  double  sulphates,  the  most  important  of  which 
is  the  so-called  potash  alum  or  ordinary  alum  of  commerce. 
Potash  alum  or  aluminium  potassium  sulphate  (A12SO4)3, 
K2SO4,24H2O)  is  a  colourless  crystalline  efflorescent  salt, 
made  on  a  large  scale  by  mixing  the  two  sulphates  and 
allowing  the  compound  to  crystallize  out  of  solution.  In  a 
form  known  as  "  Roman  alum  "  it  is  also  prepared  by  dis- 
solving calcined  alumstone  (alunite)  in  water,  which  leaves 
alumina  undissolved  ;  or  calcined  alumstone  can  be  dis- 
solved in  sulphuric  acid,  and  the  solution  admixed  with  the 
proper  proportion  of  potassium  sulphate. 

There  is  a  further  process  by  which  it  can  be  produced 
from  a  bituminous  mineral  known  as  alum  shale. 

Alum  is  extensively  used  in  the  dyeing  and  calico-printing 
industries.  It  is  readily  soluble  in  water,  and  when 
heated  in  the  dry  state  melts  in  its  own  water  of  crystalliza- 
tion, which  is  gradually  expelled,  and  when  the  process  is 
carried  to  a  dull  red  heat  a  white  mass  of  so-called  burnt 
alum  is  left. 

Ammonia  Alum  or  Aluminium  Ammonium  Sulphate  —  a 
compound  containing  ammonium  in  place  of  the  potassium 
of  ordinary  alum  —  is  manufactured  on  a  considerable  scale, 
using  ammonia  (as  prepared  in  gas-works)  and  sulphuric 
acid  in  conjunction  with  the  burnt  alum  shale  already 
referred  to.  This  shale  contains  iron  pyrites  (FeSa),  and 


26  ALUMINIUM  COMPOUNDS— AMALGAM 

ALUMINIUM  (Continued) — 

when  roasted  in  air,  the  sulphur  is  to  some  extent  oxidized 
to  sulphuric  acid,  which  combines  with  the  alumina. 

Ahuninic  Acetate  ( A12(C2H3O2)3) ,  or  so  called '  <  red  liqueur, " 
in  solution  is  used  as  a  mordant  in  calico  printing  and 
dyeing,  also  for  waterproofing  cloth,  etc. 

ALUMINIUM  BRONZE— See  Aluminium. 

ALUM  (CHROME)  or  Potassium  Chromium  Alum  has  the 
formula  K2SO4,Cr2(SO4)324H2O,  and  is  prepared  by 
the  addition  of  sulphuric  acid  to  potassium  dichromate 
(K2Cr2O7)  dissolved  in  water  and  then  reducing  it 
by  the  passage  of  sulphur  dioxide  gas,  with  the  result 
that  the  two  sulphates  of  potassium  and  chromium  are  left 
in  solution  and  the  so-called  alum  can  be  crystallized  out 
therefrom  in  the  form  of  dark  plum-coloured  octahedral 
crystals.  It  is  used  as  a  chrome  tanning  material,  and  in 
the  textile  industry  as  a  mordant. 

ALUM  SHALE— See  Aluminium. 

"  ALUMINO -FERRIC  " — A  mixture  of  crude  sulphates  of  iron 
and  aluminium  used  as  a  precipitating  and  clarifying  agent 
in  the  treatment  of  sewage  and  refuse  liquids. 

ALUMS — See  Aluminium. 

ALUNITE  or  ALUMSTONE — A  natural,  greyish,  hydrated 
basic  potassium  alum  (A12(SO4)3,K2SO4,2A12O3,8H2O) 
found  at  Tolfa  and  elsewhere  in  Italy,  in  the  United 
States,  etc. 

ALLUVIAL  ACTION — The  action  of  water  and  air  on  rocks, 
attended  with  the  formation  of  mineral  deposits.  (See  Clay.) 

AMALGAM — The  name  given  to  any  combination  of  other 
metals  with  mercury.  Gold  and  lead,  for  example,  are  both 
somewhat  easily  dissolved  by  liquid  mercury  in  varying 
proportions ;  such  combinations,  however,  are  probably  not 
definite  chemical  compounds,  but  mere  mixtures.  The 
potassium  and  sodium  amalgams  decompose  water,  giving 
off  hydrogen,  and  are  frequently  used  as  reducing  agents. 
An  amalgam  composed  of  25  per  cent,  zinc,  25  per 
cent,  tin,  and  50  per  cent,  mercury  is  used  as  a  dental 
cement,  and  in  the  construction  of  electrical  machines. 
Amalgams  of  gold  and  copper  are  also  used  by  dentists  as 
stoppings  for  teeth,  and  tin  amalgam  is  employed  for 
silvering  mirrors.  There  is  a  native  amalgam  of  mercury 
and  silver  in  which  the  proportion  of  silver  ranges  from 
2 7 '5  to  95*8  per  cent.,  and  a  native  gold  amalgam  con- 


AM  ALGA  M—A  MIDES  27 

AMALGAM  (Continued)— 

taining  from  39  to  42-6  per  cent,  is  found  in  California  and 
Colorado. 

AMATOL — See  Explosives. 

AMBER  or  SUCCINITE  (C10H8O)— A  yellow,  resin-like  com- 
bustible substance  of  probably  vegetable  origin,  found  upon 
some  sea-shores,  including  the  Prussian  coast,  an'd  as  a 
fossil  from  the  extinct  conifer  Pinus  succinifer  (Goppert)  in 
certain  alluvial  soils.  Its  usual  position  is  in  beds  of  brown 
coal  formation  of  lower  Tertiary  Age.  It  becomes  electri- 
fied by  friction,  and  finds  use  in  the  construction  of  pipe 
mouthpieces,  the  bowls  of  Turkish  pipes,  and  amber  neck- 
laces. It  is  also  used  to  some  extent  in  the  preparation  of 
amber  varnishes  and  amber  spirit- varnishes.  It  contains 
from  3  to  4  per  cent,  succinic  acid,  and  yields  by  destructive 
distillation  so  called  amber  oil,  which  has  a  sp.  gr.  of  from 
9'i5  to  9*75,  consisting  mainly  of  phenols. 

AMBERGRIS — A  greyish-brown  organic  substance  found  in  the 
intestinal  tract  of  the  sperm  whale,  soluble  in  alcohol,  and 
greatly  valued  by  perfumers  on  account  of  its  fine  musk- 
like  scent ;  sp.  gr.  0*908  to  0*920,  melting  at  about  40°  C. 

AMETHYST — A  native  form  of  silica  coloured  with  iron  and 
other  metallic  oxides. 

AMIDES,  or  acid  amides,  are  amino  compounds  containing 
the  group  or  radical  NH2.  For  instance,  urea  or  carba- 
mide (CH^O  or  NH2,CO,NH2)  is  the  amide  of  carbonic 
acid,  and  is  prepared  by  heating  ammonium  carbamate  to 
135°  C.,  thus: 

O  =  CO(NH2)2  (Urea)  +  H20  (water). 

An  acid  amide  is  the  result  of  introducing  the  amido  group 
(NH2)  in  place  of  the  hydroxyl  radical  of  certain  compounds. 

Acetamide  (C2H5NO  or  CH3,CO,NH2)  is  a  crystalline 
deliquescent  body  derived  from  acetic  acid,  which  is  soluble 
in  water  and  alcohol  and  melts  at  82°  C. 

Benzamide  (C6H5CO,NH2)  is  a  crystalline  substance 
soluble  in  water  and  alcohol,  with  a  melting-point  of  130°  C. 

Formamide  or  Methane-amide  (CH3NO)  may  be  shown 
as  HCO,NH2,  being  derived  from  H,CO,HO  or  CH2O2 
(formic  acid),  and  the  liquid  when  heated  quickly  splits  up 
into  carbon  monoxide  and  ammonia. 

Succinamide  is  C4H8O2  or  C2H4(CO)2(NH2)2. 

(See  also  Amines  and  Imides.) 


28  AMIDOL— AMINES 

AMIDOL  (diaminophenol  dihydrochloride,  (C6H8N2O,2HC1) 
is  used  with  sodium  sulphate  as  a  photographic  developing 
agent. 

AMIDOPYRIN  (dimethylaminoantipyrine) — A  medicinal  agent. 

AMINES  (nitrogen  or  ammonia  bases) — Substances  containing 
the  group  NH2  as  in  the  primary  amines,  and  distinct  from 
the  so-called  acid  amides.  They  constitute  an  important 
class  of  chemical  bodies,  and  are  intimately  connected  with 
the  alkaloidal  bases  or  alkaloids.  They  have  a  more  or 
less  ammoniacal  odour,  produce  white  clouds  with  acid 
vapour  as  does  ammonia,  and  combine  with  hydrochloric 
and  other  acids  to  form  salts.  Like  many  of  the  alkaloids, 
they  yield  double  platinum  chlorides.  They  are  divided  or 
classified  into  a  number  of  groups,  of  which  the  "primary  " 
one  includes  methylamine  and  ethylamine,  which  are  pro- 
duced by  heating  methyl  and  ethyl  cyanates  respectively 
with  potash  solution,  etc. 

Methylamine  (CH5N  or  CH3NH2)  is  found  amongst  the 
products  of  bone  distillation  and  many  decompositions  of 
alkaloidal  bodies  by  barium  hydrate.  It  is  strongly  basic, 
very  soluble  in  water,  possesses  a  mixed  ammoniacal  and 
fish-like  odour,  and  is  chemically  allied  to  another  substance 
known  as  trimethylamine,  found  in  nature  in  several  plants 
and  well  known  as  a  constituent  of  herring  brine. 

Trimethylamine  (CH3)3N)  can  be  obtained  as  a  colourless 
liquefied  gas  of  fishy  ammoniacal  odour,  soluble  in  water, 
alcohol,  and  ether.  It  can  be  prepared  by  the  interaction 
of  methyl  iodide  and  ammonia,  and  is  to  be  met  with  in 
commerce  in  solutions  of  10  and  33  per  cent,  strength 
respectively. 

The  table  below  shows  the  relationship  between  the 
primary  amines : 


Name. 

Formula. 

Boiling-point. 

Methylamine 

CH3NH2 

Below  o°  C. 

Ethylamine   

C2H6,NH2 

187°  C. 

Propylamine 

C3H7,NH2 

497°  C. 

Butylamine  

C4H9,NH2 

69-0°  C. 

Octylamine   

C6HU,NH2 

1  80-0°  C. 

The  secondary  and  tertiary  amines  corresponding  to  the 
above  and  their  relationships  are  shown  by  the  following 
table  : 


A  MINES— A  MYGDALIN 
AMINES  (Continued)— 


29 


Name. 

Formula. 

Boiling-point. 

Dimethylamine 
Diethylamine 
Trimethylamine 
Triethylamine 

CH3,CH3,NH 
C2H5,C2H5,NH 
CH3,CH3,CH3.N 

^2^5'^2^5'^2^5'^ 

8.  _o  f» 
5    *•*• 

57-5°  C. 
4°C. 
96°  C. 

Another  distinct  class  of  bodies,  yet  with  some  chemical 
relationship,  are  now  known  as  aromatic  amines  or  Aryl- 
amines,  and  of  these  aniline  is  the  best-known  member,  and 
is  regarded  as  benzene  (C6H6),  in  which  a  hydrogen  atom 
has  been  replaced  by  the  amino  group  NH2  (its  formula 
being  C6H5NH2)  ;  or  otherwise  as  ammonia  NH3,  in  which 
one  of  the  hydrogen  atoms  has  been  replaced  by  phenyl 
(C6H6).  Upon  this  latter  view  it  is  sometimes  called 
phenylamine.  (See  Amides.) 

AMINO-ACIDS— A  class  of  substances  derived  from  fatty 
acids  by  the  exchange  of  an  amino  group  for  a  hydrogen 
atom  in  the  hydrocarbon  radical.  For  example,  acetic 
acid  (CH3.CO2H)  becomes  CH2(NH2).CO2H  (amino-acetic 
acid).  Another  name  for  this  compound  is  glycocoll  (see 
Glycocoll).  Amino-acids  are  the  chief  hydrolytic  product 
of  the  proteins,  and  amongst  these  tryptophane  is  of  peculiar 
interest,  as  a  supply  of  this  substance  in  food  has  been 
shown  to  be  necessary  by  certain  experiments  made  on 
animals.  (See  Proteins,  Vitamines,  and  Foods.) 

AMINO-ACETIC  ACID— See  Glycocoll  (glycine).  * 
AMMONAL— See  Explosives. 
AMMONIA  LIQUOR— See  Coal. 

AMMONIA-OLEIN — A  commercial  form  of  sulphonated  castor 
oil. 

AMMONIA-SODA  PEOCESS— See  Sodium. 

AMMONIUM  AND  ITS  COMPOUNDS— See  Nitrogen  Com- 
pounds. 

AMORPHOUS— Without  crystalline  form. 
AMPHIBOLE— See  Hornblende. 

AMYGDALIN — A  glucoside,  being  a  white  crystalline  sub- 
stance found  in  the  bitter  almond,  and  which,  by  the  action 
of  an  enzyme  present  in  the  tissue  of  the  almond  named 


30  A  MYGDA  LIN—  A  MYLOPSIN 

AMYGDALIN  (Continued)— 

emulsin  (synaptase),  is  decomposed  in  the  presence  of 
water  into  a  number  of  products,  including  glucose 
(C6H1206). 

Amygdalin  is  one  of  a  series  of  so-called  glucosides,  all 
of  which  yield  glucose  by  similar  decomposition. 

The  bitter  almond  is  odourless,  but  directly  it  is  crushed 
in  water  this  decomposition  takes  place,  and  a  characteristic 
odour  is  produced  indicative  of  the  products  which  are 
formed.  (See  Almond  Oil  and  Glucosides.) 

AMYLACEOUS—  See  Gums,  Starches,  and  Cellulose. 

AMYL  ACETATE  (C7H14O2  or  CH3CO2C5HU)—  An  alco- 
holic solution  of  this  substance  forms  the  essence  of  pears. 
It  is  produced  by  the  slow  action  of  acetic  acid  upon  amyl 
alcohol,  and  is  made  by  distilling  potassium  acetate  or  lead 
acetate  in  admixture  with  amyl  alcohol  and  strong  sul- 
phuric acid.  It  is  a  colourless  liquid,  of  sp.  gr.  0*866, 
nearly  insoluble  in  water,  having  an  ethereal  aromatic 
odour,  and  is  largely  used  for  flavouring  purposes  and  as  a 
solvent  of  cellulose,  etc. 

AMYL  ALCOHOL—  The  pure  alcohol  has  the  formula  C5H12O, 
but  the  commercial  article  is,  or  was,  a  mixture  prepared 
from  fusel  oil.  It  is  made  in  large  quantities  as  a  solvent 
of  cellulose  for  making  so-called  "  dope,"  for  use  in  con- 
nection with  the  manufacture  of  aeroplanes.  It  is  a  clear, 
colourless  liquid,  of  sp.gr.  0-810,  boiling  at  130°  C.,  soluble 
in  water,  alcohol,  and  ether  ;  obtained  as  a  by-product  in 
the  production  of  ordinary  alcohol  from  starch  or  sugar  by 
fermentation. 

AMYL  BUTYRATE  (C4H7O2C5Hn)—  A  colourless  liquid  of 
sp.  gr.  0-859,  and  boiling-point  about  154°  C.  ;  used  as  a 
flavouring  principle,  and  in  the  making  of  liqueurs. 


AMYL  NITRITE  (CgH^NOa)—  A  yellowish  liquid,  soluble  in 
alcohol  and  ether,  of  sp.  gr.  0-880,  which  boils  at  97°  to 
99°  C.,  and  is  used  as  a  stimulant  inhalant  in  cases  of 
angina  pectoris  ;  also  in  perfumery. 

AMYLOPSIN,  otherwise  known  as  pancreatic  diastase,  is  one 
of  the  enzymes  contained  in  pancreatin  capable  of  con- 
verting starch  into  dextrin  and  maltose.  It  acts  best  in 
neutral  or  slightly  alkaline  media  at  a  temperature  of 
between  30°  and  45°  C.,  and  is  destroyed  at  65°  C. 


AMYL  SALICYLATE— ANHYDROUS  31 

AMYL  SALICYLATE  (C7H5O3 :  C5Hn)— A  colourless  or 
slightly  yellow  liquid,  of  sp.  gr.  1*045,  an(^  boiling-point 
about  270°  C. ;  soluble  in  alcohol  and  ether  ;  used  as  a 
flavouring  material. 

AMYLUM— See  Starch. 

ANALOGOUS — Having  resemblance  or  relation. 

ANALYSIS — The  decomposition  of  substances  into  their 
constituent  parts  or  elements.  The  term  is  also  employed 
in  respect  of  the  processes  by  means  of  which  chemists 
ascertain  the  constituents  of  substances. 

ANASTASE — A  mineral  form  of  nearly  pure  titanium  oxide 
(Ti02). 

ANDALUSITE — A  mineral  form  of  crystallized  aluminium 
silicate  (Al2O3,SiO2),  found  in  Andalusia  (Spain)  and  else- 
where. 

ANEMOMETER — An  instrument  or  device  to  measure  the 
direction  and  force  of  the  wind. 

ANGELICA  (Archangelica  officinalis) — A  plant,  parts  of  which 
are  used  for  flavouring  purposes  and  in  the  rectification 
and  compounding  of  gin.  The  root  contains  angelic  acid 
(C5H8O2),  a  crystalline,  colourless  substance,  which  melts 
at  45°  C.,  and  is  sometimes  used  in  medicine. 

ANGLESITE— Native  lead  sulphate,  found  in  Spain,  North 
America,  and  Cumberland,  probably  produced  by  the 
oxidation  of  galena  (lead  sulphide). 

ANGOSTURA — A  bitter  principle  in  the  nature  of  an  organic 
base,  obtained  from  the  bark  of  Angustura  (Cusparia  febri- 
fuga,  or  trifoliata).  The  bark  is  stated  to  contain  cusparine 
(C20H19N02),  etc. 

ANHYDRIDES  — Chemical  substances  resulting  from  the 
abstraction  of  the  elements  of  water  from  other  substances. 
For  instance,  the  metallic  hydrates  or  hydroxides,  of  which 
potassium  hydroxide  (KHQ)  is  illustrative,  give  the  cor- 
responding oxides  or  anhydrides  by  deprivation  of  water ; 
thus,  2KHO  =  K20  +  H20. 

Again,  acetic  anhydride  (C4H6O3)  is  similarly  obtained 
from  acetic  acid ;  thus,  2C2H4O2  =  C4H6O3  +  H2O. 

In  a  sense  also  cymene  (C10H14)  may  be  regarded  as  the 
anhydride  of  camphor,  as  by  distillation  with  phosphoric 
anhydride  it  yields  cymene,  C10H16O  =  C10H14  +  H2O. 

ANHYDRITE— See  Calcium. 

ANHYDROUS— Devoid  of  water  as  a  constituent. 


32  ANILINE— ANIMAL  MATTER 

ANILINE  (amino-benzene  or  phenylamine,  C6H5,NH2)  is 
an  important  base  from  which  a  great  number  of  dyes  are 
prepared,  and  is  manufactured  by  acting  on  nitrobenzene 
with  iron  filings  and  hydrochloric  acid,  and  subsequently 
distilling  with  steam  after  the  addition  of  lime.  The 
following  equation  expresses  the  chemical  change  that  thus 
takes  place : 

C6H6N02  +  3Fe+6HCl=C6H5,NH2  +  2H20  +  3FeCl2. 

In  a  more  modern  process  the  reduction  of  nitrobenzene 
is  effected  by  passing  its  vapour,  mixed  with  hydrogen  gas, 
over  a  catalyst  at  an  appropriate  temperature. 

The  aniline  oil  thus  produced  is  the  base  or  starting- 
point  from  which  a  great  number  of  other  "  intermediates  " 
for  dyes  are  prepared,  including  dimethylaniline  and 
diethylaniline,  and  these  yield  in  turn  a  great  number  of 
so-called  basic  dyes,  such  as  methyl  violet,  methylene  blue, 
and  malachite  green. 

The  physical  constants  of  pure  aniline,  as  recently  deter- 
mined, are  as  follows :  freezing-point,  6-24°  C. ;  boiling- 
point,  184-32°  to  184-39°  C. ;  sp.  gr.j  1-0268 ;  and  refractive 
index  at  20°  C.,  1-5850. 

Aniline  is  an  oily,  colourless  liquid  of  peculiar  odour, 
which  darkens  on  exposure  to  air,  and  finally  dries  up 
into  a  resin-like  mass.  It  is  soluble  i  in  31  parts  water, 
in  alcohol  and  ether,  and  behaves  as  a  base  like  ammonia, 
but  is  weaker,  poisonous,  and  forms  a  number  of  combina- 
tions, including  aniline  hydrochloride  (CgH5,NH2,HCl). 
By  boiling  aniline  with  glacial  acetic  acid,  a  substance 
named  "  acetanilide "  (C6H5,NH,CO,CH3)  is  produced. 
This  is  otherwise  known  under  the  medicinal  name  of 
"  antifebrine,"  and  is  a  beautiful  crystalline  substance, 
readily  soluble  in  hot  water,  alcohol,  ether,  and  chloroform, 
melting  at  115°  C. 

There  are  several  homologues  of  aniline.  (See  also 
Amines.) 

ANILINE  SALT— Aniline  hydrochloride  (C6H5,NH2,HC1), 
which  crystallizes  in  large  colourless  plates,  and  can  be 
distilled  without  change.  It  melts  at  198°  C.,  and  is 
soluble  in  water,  alcohol,  and  ether, 

ANIMAL  CHARCOAL— See  Carbon. 
ANIMAL  LIFE— See  Air. 
ANIMAL  MATTER— See  Carbon. 


ANIME  RESIN—ANTHRACENE  33 

ANIME  RESIN  (or  gum)  is  of  several  varieties  (East  Indian, 
Zanzibar,  West  Indian,  and  South  American),  and  is  said 
to  be  used  for  fumigation,  also  in  the  making  of  varnishes. 
Sp.  gr.  i -06,  and  melting-point  240°  to  250°  C. 

The  West  Indian  variety  is  the  produce  of  a  tree  known 
as  the  Hymencza,  Courbaril.     (See  Copal.) 

ANIONS.— See  Electricity. 

ANISEED  OIL  contains  a  substance  called  anethol  (C10H12O), 
is  used  in  flavouring  certain  liqueurs,  and  is  made  from  the 
seed  of  Pimpinella  anisum  and  the  China  or  star  anise 
(Illicmm  anisatum)  by  distillation  with  water.  It  is  a  thick 
yellowish,  syrupy  liquid  of  sp.  gr.  0-975  to  0*990,  and  re- 
fractive index  1-54  to  1-56,  of  peculiar  aromatic  smell  and 
taste.  The  yield  of  oil  from  the  seeds  is  about  2-4  per 
cent.  Anethol  is  also  obtained  from  fennel  (Anethum 
fcenicidum)  and  tarragon  (Artemisia  dracimcukis). 

ANNATTO — A  colouring  matter  made  from  the  seeds  of  the 
Bixa  orellano,  cultivated  in  Guiana,  St.  Domingo,  and  the 
Indies.  It  dissolves  in  alcohol  with  an  orange-red  colour, 
and  is  said  to  contain  a  crystalline  yellow  substance  named 
bixin,  which  in  the  presence  of  alkalies  absorbs  oxygen 
and  turns  red.  It  is  a  fugitive  colour,  used  in  dyeing  and 
for  colouring  cheese,  etc. 

ANORTHITE — A  mineral  compound  silicate  of  aluminium 
and  calcium. 

ANTHOCYANINS— See  Plant  Colouring  Matters. 

ANTHRACENE  (C14H10  or  CgH4.CH.CH.C6H4)--A  product 
of  the  destructive  distillation  of  coal,  present  in  coal-tar 
to  the  extent  of  from  J  to  nearly  £  per  cent.  In  the  pure 
state  it  is  a  yellow  crystalline  body,  and  exhibits  a  fine  blue 
fluorescence.  It  is  obtained  from  the  so-called  anthracene 
oil,  which  distils  over  between  270°  and  400°  C.,  and  forms 
about  12  to  17  per  cent,  of  the  tar.  Upon  cooling,  the 
crystals  of  anthracene  are  separated  from  the  oily  mother- 
liquor  by  pressing  and  centrifugalizing.  This  crude  pro- 
duct, containing  about  40  per  cent,  anthracene,  is  further 
purified  from  naphthalene,  phenanthrene,  crysene,  carba- 
zole,  and  other  bodies  with  which  it  is  associated,  by 
exposure  to  steam  when  placed  in  a  hydraulic  press,  after 
which  it  is  washed  with  a  mixture  of  solvent  naphtha 
mixed  with  pyridine  bases.  In  this  way  a  product  con- 
taining about  90  per  cent,  anthracene  can  be  obtained. 
The  chemically  pure  anthracene  is  obtained  by  grinding 
up  the  crude  substance  with  caustic  potash  and  lime,  and 

3 


34  A  NTHRA  CENE—A  NT  I  MO  NY 

ANTHRACENE  (Continued)— 

redistillation,  the  product  being  finally  washed  with  solvent, 
and  sublimed.  Anthracene  melts  at  216°  C.,  boils  at 
351°  C.,  and  is  used  for  making  various  aniline  colours, 
especially  Turkey  red.  (See  Alizarin.) 

ANTHRACITE — A  hard  coal,  which  burns  with  little  smoke 
and  flame,  and  contains  from  85  to  95  per  cent,  carbon. 

ANTHRAQUINONE  (C14H8O2  or  C6H4(CO)2C6H4)— A  product 
of  the  oxidation  of  anthracene.  It  crystallizes  in  yellow 
needles,  melts  at  285°  C.,  and  is  soluble  in  alcohol,  ether, 
and  acetone. 

ANTICHLOR  —  A  term  used  by  bleachers  in  respect  of 
chemicals,  such  as  sodium  sulphite  and  sodium  thiosulphate, 
employed  for  the  purpose  of  obviating  any  deleterious  after- 
effects of  the  action  of  chlorine  preparations  used  in  bleach- 
ing operations  by  removing  the  residual  chlorine. 

ANTIFEBRINE— See  Acetanilide. 

ANTIMONY  (Stibium,  Sb)  and  its  compounds — Atomic  weight, 
120  ;  sp.  gr.,  67 ;  melting-point,  630°  C.  Antimony  is  found 
naturally  in  small  quantities,  but  in  greater  quantities  it 
exists  combined  with  oxygen  as  so-called  white  antimony 
(Sb2O3),  and  in  another  form  as  antimony  ochre  (Sb2O4).  Its 
chief  ore  is  the  trisulphide  stibnite  (Sb2S3),  or  grey  antimony 
ore,  whilst  other  combinations  with  oxygen  and  sulphur  are 
antimony  blende  (Sb2O3,2Sb2S3),  and  red  antimony  (kermisite). 
Antimony  mining  is  conducted  on  a  considerable  scale  in 
Bolivia,  China,  Mexico,  the  United  States  of  America,  and 
elsewhere. 

Antimony  is  a  bright  bluish-white  crystalline  metal, 
largely  used  in  making  alloys.  Type  metal  consists  of  lead 
75  parts,  antimony  20  parts,  and  tin  5  parts.  Stereotype 
metal  consists  of  lead  112,  antimony  18,  tin  3  parts;  and 
Britannia  metal,  tin  140,  copper  3,  antimony  9,  all  of  which 
give  fine  and  sharp  castings. 

Antimony  is  also  used  for  producing  the  appearance  of 
polished  steel  on  papier-mache  ;  the  tetroxide  is  used  for 
rendering  enamels  opaque,  and  the  trioxide  for  colouring 
glass,  and  as  a  paint.  The  red  sulphide  is  used  for  vulcan- 
izing rubber  and  for  preparing  the  striking  surface  on 
safety-match  boxes.  (See  Phosphorus.) 

Alloyed  with  lead,  it  has  been  largely  used  in  the  great 
war  in  preparing  shrapnel  bullets,  and  the  sulphide  in 
making  shell  primers  and  as  a  smoke  producer. 

The  metal  is  prepared  by  heating  the  broken-up  native 


ANTIMONY— ANTIPYRINE  35 

ANTIMONY  (Continued)— 

trisulphide  with  half  its  weight  of  scrap  iron  in  plumbago 
crucibles,  when  iron  sulphide  is  formed,  and  the  metallic 
antimony  set  free,  as  follows : 

Sb2S3  +  3Fe  =  2Sb  +  3FeS 

or  the  selected  sulphide  separated  from  the  associated 
rocky  matter  of  the  ore  can  be  mixed  with  charcoal  or  coal 
and  heated  in  a  reverberatory  furnace  ;  the  sulphur  in 
this  way  is  burnt  off  as  sulphur  dioxide. 

Antimony  is  a  bad  conductor  of  heat  and  electricity  and 
is  not  acted  upon  by  the  air.  When  strongly  heated,  it 
burns  in  air  or  oxygen  with  a  brilliant  light  and  forms 
antimony  trioxide  (Sb2O3).  When  thrown  into  chlorine  gas 
it  takes  fire  and  forms  antimony  trichloride  (SbCl3). 

There  are  two  chlorides  of  antimony — viz.,  the  tri- 
chloride (SbCl3),  which  is  used  as  a  mordant  and  for 
bronzing  iron,  etc.,  and  the  pentachloride  (SbClg) ;  and  three 
oxides — viz.,  the  trioxide  (Sb2O3),  the  tetroxide  (Sb2O4), 
and  the  pentoxide  (Sb2O6). 

The  trichloride  (butter  of  antimony)  is  a  colourless  crys- 
talline body,  soluble  in  water  and  alcohol,  and  is  used  in 
bronzing  iron,  as  a  mordant  for  making  lakes,  and  colouring 
zinc  black. 

When  the  trioxide  is  dissolved  in  a  boiling  solution  of 
potassium  hydrogen  tartrate  (cream  of  tartar),  potassium 
antimony  tartrate  or  tartar  emetic  is  formed.  This  compound 
is  used  medicinally. 

Two  sulphides  are  known — viz.,  the  trisulphide  (Sb2S3), 
which  is  used  as  a  pigment,  and  the  pentasulphide  (Sb2S5). 
The  trisulphide  occurs  in  nature  as  the  black  crystalline 
stibnite,  but  when  precipitated  from  solutions  it  is  an  orange- 
red  compound. 

Antimony  hydride  or  antimoniuretted  hydrogen  (SbH3) 
is  produced  when  an  antimonial  solution  is  brought  into 
contact  with  zinc  and  sulphuric  acid.  It  is  a  colourless 
gas  of  offensive  odour,  which  can  be  obtained  also  in  liquid 
and  solid  forms. 

Antimony  lactate  (Sb(C3H5O3)3)  is  soluble  in  water,  and 
is  used  as  a  mordant. 

Antimony  forms  compounds  with  the  alkyls  similar  to 
those  of  arsenic,  for  example,  trimethyl-stibine,  Sb(CH3)3, 
a  disagreeable  inflammable  liquid. 
ANTIPYRINE  (Phenazone) 

(CUH12N20  or  C6H5(CH3)2C3HN20) 
A  white  crystalline  substance  which  melts  at  113°  C,  is 


36  ANTIPYRINE—ARACHIS  OIL 

ANTIPYRINE  (Continued)— 

soluble  in  water,  alcohol,   and  ether,  and  constitutes  an 
excellent  febrifuge  and  an  alleviative  to  neuralgic  pains. 

ANTISEPTICS — Preventives  of  septic  poisoning  or  decom- 
position in  the  nature  of  putrefaction. 

APATITE — A  mineral  compound  of  phosphate  and  fluoride  of 
calcium^(3Ca3(PO4)2,CaF2),  occurring  in  the  United  Srates 
and  Canada,  etc. 

APIOL — An  oil  obtained  from  the  fruit  of  parsley,  pale  green 
in  colour,  sometimes  used  as  a  diuretic. 

APPARATUS — The  utensils  and  appliances  used  by  chemists. 

AQUADAG— See  Lubricants. 

AQUA  FORTIS  —An  old  name  for  nitric  acid. 

AQUA  REGIA — A  mixture  of  nitric  and  hydrochloric  acids — a 
very  powerful  solvent.  Gold  and  platinum,  for  example, 
can  be  dissolved  by  this  mixture,  which  is  commonly  made 
of  1 8  parts  and  82  parts  of  the  respective  acids. 

AQUEOUS  VAPOUR  (Atmospheric)— The  water  or  moisture 
held  dissolved  in  vaporous  solution  in  the  air.  (See  Air.) 

ARABINOSE  (C5H10O5)— A  white  crystalline  body  soluble  in 
water,  is  a  constituent  of  many  plants,  and  can  be  made  by 
boiling  gum  arabic  or  cherry  gum  with  dilute  sulphuric  acid. 

ARACHIDIC  (ARACHIC)  ACID  (C20H40O2)— A  member  of  the 
normal  fatty  acids,  found  in  the  oil  of  the  earth-nut 
(Arachis  hypogcea).  It  is  a  crystalline  body  which  melts  at 
75°  C.,  and  is  soluble  in  boiling  alcohol  and  in  ether.  (See 
Arachis  Oil.) 

ARACHIS  OIL  (Earth-nut  Oil,  Pea-nut  Oil)— A  fatty  oil,  of 
which  there  are  many  grades,  expressed  from  the  fruit  of 
Arachis  hypogcea,  a  leguminous  plant  indigenous  in  India, 
South  Africa,  and  South  America.  It  is  pale  yellow,  of 
agreeable  odour,  of  non-drying  character;  is  soluble  in 
alcohol,  ether,  benzol,  and  carbon  disulphide,  has  a  sp.  gr. 
of  0-916  to  0-925,  a  saponification  value  185  to  196, 
and  iodine  value  92  to  101.  It  is  used  as  a  salad  oil  and 
substitute  for  olive  oil,  for  soap-making,  and  as  a  delicate 
lubricant  by  watchmakers.  Chemically,  it  is  a  glyceride  of 
ararchidic  acid. 

A  recent  examination  of  the  fatty  acids  obtained  from 
a  sample  with  an  iodine  value  of  86 -i  showed  the  presence 
of  2 -3  arachidic  acid,  1-9  lignoceric  acid,  4*5  stearic  acid, 
4-0  palmitic  acid,  79-9  oleic  acid,  and  7*4  linoleic  acid. 


ARCHIL— ARRACK  37 

ARCHIL — A  purple  dye  obtained  from  many  kinds  of  lichens, 
including  the  geni  Rocella  and  Variolaria  orcina,  etc.,  a  number 
of  which  contain  certain  colourless  acids  which  are  capable 
of  transformation  into  a  colourless  substance  termed  orcin, 
which,  by  the  action  of  air  and  ammonia,  is  changed  into 
the  purple  body  called  orcein  (C28H24N2O7) — the  colouring 
principle  of  archil.  The  Rocella  pemviana  occurs  in  abund- 
ance around  Magdalena  Bay  (Lower  California),  as  much  as 
100,000  tons  being  harvested  in  1917.  The  lichen  is  torn 
from  the  trees,  and,  after  drying,  is  ground  to  a  coarse 
powder,  and  then  macerated  during  several  weeks  in 
dilute  ammonia  with  frequent  stirring.  It  is  expensive 
and  perishable,  and  is  used  as  a  dye  for  cloth  and  silk 
Marble,  however,  stained  with  it  retains  the  colour  well. 
Cudbear  is  a  variety  of  archil,  and  the  bright  blue  it  gives 
to  silks  is  said  to  be  much  more  permanent. 

ARECA  (Betel)— A  genus  of  plants,  including  the  Areca 
catechu,  the  ground-nut  of  which  contains  numerous  alka- 
loids and  is  used  as  a  vermifuge,  especially  for  dogs. 

ARGENTITE  ("  Silver  glance  ") — A  native  form  of  silver 
sulphide  (Ag2S)  occurring  in  cubic  crystals,  containing 
87  per  cent,  silver,  found  in  several  of  the  United  States  of 
America. 

ARGILLACEOUS— Clayey  in  character. 

ARGOL — Crude  tartar  as  deposited  in  wine  casks  or  at  the 
bottoms  of  fermenting  vessels.  (See  Tartar.) 

ARGON  (A) — Atomic  weight,  39*88.  Argon  is  a  recently  dis- 
covered element  found  present  in  the  gaseous  state  in 
the  air  to  the  extent  of  rather  less  than  i  per  cent,  by 
volume,  and  also  in  minute  quantity  in  Bath  and  other 
mineral  spring  waters.  It  is  isolated  by  processes  which 
remove  the  oxygen  and  nitrogen  respectively.  It  is  a 
remarkably  inert  substance,  and  has  been  liquefied  and 
frozen  to  a  white  solid.  No  chemical  combinations  of  it 
are  known.  The  density  of  the  gas  is  19*94,  an(^  **  *s 
soluble  in  water  to  the  extent  of  4*1  volumes  in  100  at 
15°  C.  It  boils  at  187°  below  o°  C.  According  to  Ramsay, 
the  fractional  distillation  of  argon  yields  traces  of  other 
gases  having  distinct  spectra,  and  to  these  he  gave  the 
names  of  Neon,  Xenon,  and  Krypton. 

ARRACK — A  spirituous  drink  prepared  by  the  fermentation  of 
an  infusion  of  rice.  A  similar  preparation  known  as  "  palm 
wine  "  is  made  in  Ceylon  from  cocoa-nut  toddy. 


38  A  RRA  GONITE—A  RSENIC 

ARRAGONITE-See  Calcium. 
ARROWROOT— See  Starch. 

ARSENIC  (As)  and  its  compounds  —  Atomic  weight,  75; 
sp.  gr.,  5-62;  melting-point,  850°  C.  (under  pressure). 
Arsenic  occurs  in  nature  in  the  metallic  state  and  in  com- 
bination with  sulphur  as  realgar  (As2S2)  and  orpiment  (As2S3). 
It  is  also  found  in  other  combinations  with  iron  (arseno- 
pyvite  or  arsenical  iron,  FeAs2  and  Fe4As3),  and  mispickel 
(FeS2  +  FeAs2),  with  nickel  (kupfernickel,  NiAs  and  NiAs2), 
and  with  cobalt.  Arsenopyrite  occurs  abundantly  in  Ontario, 
and  there  are  orpiment  mines  in  Chitral,  while  some  arsenic 
is  produced  in  Queensland,  Western  Australia,  United 
States,  France,  and  Cornwall,  but  it  is  chiefly  produced 
from  the  silver-cobalt-nickel-arsenic  ores  of  the  Ontario 
cobalt  district  as  a  by-product. 

It  is  of  grey  colour,  sublimes  at  450°  C.,  and  is  used 
for  mixing  in  small  proportion  with  lead  when  melted  to 
make  shots,  which  are  harder  than  those  made  with  pure 
lead.  It  has  a  vapour  density  of  150. 

The  metal  is  manufactured  from  arsenical  pyrites  by 
roasting  it  in  vessels  fitted  with  suitable  condensers  for 
receiving  the  arsenic  which  is  liberated  and  volatilized  by 
the  splitting  up  that  occurs,  ferrous  sulphide  being  left 
behind — 

FeS2,FeAs2  =  2FeS  +  2  As. 

In  its  ordinary  form  it  is  crystalline  and  is  a  good  con- 
ductor of  heat  and  electricity,  but  an  amorphous  form 
is  also  known. 

Arsenic  Hydride  (AsH3),  otherwise  known  as  arsine  and 
"  arseniuretted  hydrogen,"  is  an  offensive  smelling  colour- 
less poisonous  gas  which  can  be  prepared  by  the  action  of 
dilute  hydrochloric  or  sulphuric  acid  upon  an  alloy  of 
arsenic  and  zinc.  It  burns  with  a  bluish  flame,  forming 
water  and  arsenious  oxide,  but  if  the  amount  of  air  is 
limited,  metallic  arsenic  is  deposited.  The  so-called  Marsh's 
test  is  based  on  this  change. 

Arsenious  Oxide  (As2O3)  is  manufactured  as  a 
secondary  product  in  the  roasting  of  many  arsenical 
ores  for  the  recovery  of  the  associated  metals — nickel, 
cobalt,  silver,  and  tin — large  quantities  being  pro- 
duced in  the  United  States  of  America,  chiefly  at  Bute 
(Mass.),Tintic  (Utah),  and Tacona( Wash.),  being  recovered 
from  the  smelter  fume.  It  is  commonly  known  as  "white 
arsenic,"  and  is  used  not  only  in  the  manufacture  of  certain 


ARSENIC— A  SBESTOS  39 

ARSENIC  (Continued)— 

pigments  and  flint  glass,  but  largely  for  the  preparation  of 
sodium  arsenite  (Na3AsO3),  which  is  made  by  dissolving 
the  oxide  in  caustic  soda  or  sodium  carbonate  solution,  and 
used  as  a  weed  -  killer  and  horticultural  insecticide. 
Arsenious  oxide  is  very  poisonous,  and  so  also  are  most  of 
the  arsenical  compounds.  The  world's  production  of  white 
arsenic  has  been  estimated  as  between  20,000  and  25,000 
tons. 

Arsenic  Pentoxide  (As2O5)  is  obtained  by  oxidizing  arsen- 
ious  oxide  with  nitric  acid. 

Arsenic  Bisulphide  (As2S2)  is  an  orange-red  powder  in- 
soluble in  water  (prepared  by  roasting  mispickel  and  iron 
pyrites  and  sublimation),  used  in  a  number  of  industries, 
including  calico-printing,  the  manufacture  of  leather,  shots, 
and  paints,  and  as  a  depilatory  agent.  It  is  also  found 
native  as  Realgar. 

The  trisulphide  (As2S3)  (found  native  as  Orpiment)  and 
the  pentasulphide  (As2S5)  are  yellow  substances  insoluble 
in  water,  and  are  both  used  as  pigments  in  paint-making. 

Arsenic  resembles  phosphorus  and  nitrogen  in  the  sense 
that  it  forms  analogous  compounds  with  alkyl  radicles,  as, 
for  example,  tri- methyl  arsine,  which  is  analogous  to  tri- 
methlyamine  and  tri-methyl  phosphine.  (See  Cacodyl.) 

ARSINE— See  Arsenic  Hydride,  p.  38. 

ARTIFICIAL  SILK— See  Cellulose  and  Silk  (artificial). 

ARUM— See  Starch. 

ASAFCETIDA — A  resinous  gum  from  the  root  of  the  Ferula 
asafcetida,  an  umbelliferous  plant  which  grows  in  Thibet, 
Persia,  and  Turkestan.  It  has  a  strong  offensive  odour,  is 
much  more  soluble  in  alcohol  than  in  water,  and  upon  dis- 
tillation with  water,  yields  about  3  per  cent,  of  a  sulphuretted 
volatile  oil  (of  sp.  gr.  0-975  to  °'99°)> to  which  its  odour  is 
due.  It  is  a  powerful  antispasmodic,  and  is  used  in 
hysterical  cases  and  in  cases  of  flatulent  distension  of  the 
bowels. 

ASBESTOS — A  fibrous  variety  of  the  mineral  amphibole,  being  a 
compound  silicate  and  aluminate  of  magnesium,  calcium 
and  iron.  The  name,  however,  is  applied  not  only  to  the 
minerals  tremolite,  actinolite,  and  other  varieties  of  amphibole, 
but  to  fibrous  forms  of  pyroxene,  the  different  mineral 
crocidolite  (distinguished  by  its  large  proportion  of  ferrous 
iron  constituent)  and  to  chrysotiley  a  fibrous  variety  of  ser- 


40  ASBESTOS—ASHES 

ASBESTOS  (Continued)— 

pentine   which   differs   in   that   it   is  a  hydrated   silicate, 
whereas  all  the  others  are  anhydrous. 

Most  of  the  commercial  supplies  come  from  the  Province 
of  Quebec,  but  asbestos  occurs  also  in  China,  Italy,  and 
many  of  the  United  States  of  America,  while  chrysotile 
deposits  are  found  in  Russia,  and  South  Africa  yields 
supplies  not  only  in  that  form,  but  also  as  crocidolite  and 
amosite. 

Asbestos  is  manufactured  not  only  into  cloth  and  fabrics 
for  fireproof  clothing  and  theatre  curtains,  but  also  into 
yarn,  packing,  boiler  coverings,  and  many  other  useful 
forms  and  is  employed  in  compounding  a  number  of  build- 
ing and  roofing  materials.  It  withstands  heating  to  a  high 
temperature,  and,  as  it  is  not  acted  upon  by  many  chemicals, 
is  often  employed  in  laboratories ;  for  example,  in  the  form 
of  fibres  for  plugging  the  ends  of  glass  tubes  in  order  to 
retain  their  chemical  contents  within  prescribed  limits.  In 
the  form  of  woven  mats  or  cloths  it  is  useful  as  a  soft,  non- 
conducting material  on  which  may  be  stood  flasks  or 
beakers  containing  hot  solutions.  It  is  also  employed  as 
a  covering  for  the  central  part  of  wire  gauze  used  on  the 
top  of  iron  tripod  stands,  thus  preventing  oxidation  by 
rusting,  affording  a  softer  seat  for  glass  vessels  placed 
thereon  when  required  to  be  heated  by  lamps  below,  and 
for  the  better  distribution  of  the  flame.  In  the  fibrous  form 
it  also  finds  employment  as  a  filtering  material  wherewith 
to  plug  the  neck  of  funnels  for  separating  solid  and  liquid 
materials,  particularly  when  it  is  known  that  a  paper  filter 
would  become  easily  clogged  or  destroyed  by  the  chemical 
mixture ;  and  although  the  filtrate  may  not  be  quite  clear, 
it  then  admits  of  more  rapid  and  perfect  filtration  through 
an  ordinary  paper  filter. 

"ASEPTOL" — A  trade  name  for  an  antiseptic  solution  of  phenol 
sulphonic  acid  (C6H4(OH)SO3H). 

ASHES — All  woods,  weeds  and  vegetable  growths,  as  well  as 
coal,  peat  and  lignite,  leave  ashes  when  burned  and  all  ot 
them  contain  some  amount  of  alkali.  Potash  was  originally 
produced  from  the  ashes  of  plants  and  a  process  is  now  in 
use  for  its  recovery  from  the  coal  used  in  blast  furnaces. 
As  K2O  it  amounts  to  from  about  10  per  cent,  in  the  ashes 
of  straw  to  42  per  cent,  in  that  from  peas.  The  potash  is 
associated  with  varying  amounts  of  soda,  lime,  magnesia, 
iron  oxide,  sulphur  in  the  form  of  sulphates,  silica,  carbon 
dioxide,  and  phosphoric  acid. 


ASHES— ASPIRATOR  41 

ASHES  (Continued)— 

The  woods  which  yield  the  greatest  amount  of  potash  are 
wormwood  and  fumitory. 

ASPARAGINE  (C4H8N2O3) — An  amidated  body  contained 
in  asparagus,  potatoes,  beet-roots,  vetches,  and  the  juices 
of  other  vegetables  including  the  marsh  mallow,  liquorice 
juice,  the  tubers  of  the  dahlia,  and  the  shoots  and 
young  leaves  of  many  leguminous  plants.  It  forms  small 
hard  inodorous  crystals,  soluble  in  1 1  parts  cold  and  5  parts 
hot  water,  and  when  heated  with  strong  acids  or  alkalies,  is 
resolved  into  aspartic  acid  and  ammonia.  It  forms  certain 
definite  compounds  with  acids. 

ASPARTIC  ACID  or  AMINO-SUCCINIC  ACID  (C4H7NO4)— 
A  crystalline  body  contained  in  beet-root  molasses,  and 
found  among  the  products  of  the  decomposition  of  proteids 
by  hydrolysis.  It  also  results  from  the  hydrolysis  of  aspara- 
gine — the  acid  amide  contained  in  asparagus  and  some  other 
vegetables. 

ASPHALT — Natural  solid  or  semi-solid  bitumen,  black  or 
brownish- black,  deposits  of  which  are  found  in  many  places, 
including  Alabama,  Trinidad,  San  Valentino,  Chieti  in 
Italy,  Java,  Cuba,  Seyssel  (on  the  Rhone),  Texas,  Utah, 
Val  de  Travers  (near  Neuchatel),  Venezuela,  and  Limmer 
(near  Hanover).  It  is  supposed  to  have  been  formed  from 
the  high-boiling  mineral  oils  by  oxidation,  melts  at  from 
32°  to  100°  C.,  is  combustible  and  largely  soluble  in  naphtha 
and  turpentine.  It  is  used  for  lining  water-tanks,  in  the 
construction  of  asphalt  pavings  and  cements,  and  as  a 
component  of  some  varnishes.  The  bituminous  constituents 
of  asphalt,  which  are  insoluble  in  petroleum,  closely  resemble 
coal  in  characters,  and  are  termed  asphaitenes. 

ASPIRATOR — An  arrangement  for  aspirating  or  drawing  a 
current  of  air  or  other  gas  through  a  vessel  or  through  a 
liquid  contained  in  one.  When  only  a  small  volume  of  air 
is  wanted,  a  fitted-up  Winchester  bottle  (as  shown  in  the 
figure)  may  be  used.  A  represents  a  flask  containing  the 
liquid  through  which  it  is  desired  to  draw  the  current  of, 
say,  air ;  B  rubber  tubing  connecting  glass  tube  from  A  to 
glass  tube  going  just  through  the  cork  of  the  Winchester,  C ; 
D  glass  tube  going  to  bottom  of  C  and  joining  up  at  E  with 
a  length  of  rubber  tubing  dropping  down  into  the  sink 
of  the  laboratory,  but  fitted  at  F  with  a  pinch -cock  for 
regulating  the  flow  of  water  from  C  into  the  sink.  The 
flow  is  first  of  all  started  by  sucking  at  the  end  of  this 


42  A  SPIRA  TOR— A  TOMS 

ASPIRATOR  (Continued)— 

rubber  tubing  and  thus  drawing  the  water  from  C,  the  flow 
being   subsequently   regulated  by  closing  or  relaxing  the 


pinch-cock  (F).  In  this  manner  D  really  acts  as  a  siphon- 
tube.  (See  Siphon.) 

ASPIRIN  or  ACETOSAL— (Acetyl  Salicylic  Acid)  (C9H8O4)— 
A  white  crystalline  powder,  being  an  acetic  derivative  of 
salicylic  acid  which  exists  in  meadowsweet,  and  is  also 
manufactured  for  use  as  an  intestinal  antiseptic  and  for 
other  medicinal  applications.  It  melts  at  from  132°  to 
135°  C.,  and  is  soluble  in  alcohol  and  ether,  but  only  slightly 
soluble  in  water. 

ASSAYING — The  art  of  chemically  estimating  or  determining 
the  several  amounts  of  metals  contained  in  minerals,  ores, 
alloys,  and  metallurgical  products. 

ASTRINGENT— Bitter,  harsh  taste. 

ATACAMITE — A  native  oxychloride  of  copper  found  in  the 
form  of  light  green  rhombic  crystals  in  the  desert  of 
Atacama  in  Peru  and  elsewhere. 

ATMOSPHERE— See  Air. 

ATOMS  are  generally  described  as  the  smallest  parts  of  any 
chemical  elements  that  can  exist  in  a  state  of  combination 
or  take  part  in  a  chemical  change.  They  are  supposed  to 
be  indivisible,  although  conceivably  everything,  no  matter 
how  small,  can  be  again  divided  into  two  parts.  In  the 
past  it  was  supposed  that  all  the  atoms  of  any  one  element 
are  of  the  same  size  and  weight,  and  that  they  differ  from 
those  of  all  the  other  elements  in  mass  (weight)  and 


ATOMS— ATOMIC  WEIGHTS  43 

ATOMS  (Continued)— 

chemical  properties.  Hydrogen  is  the  lightest  in  weight, 
and  platinum  is  one  of  the  heaviest.  Oxygen  is  sixteen 
times  heavier  than  hydrogen,  and  these  relative  weights 
are  termed  their  atomic  weights.  There  is  a  rapidly 
developing  tendency  to  regard  all  matter  as  composed  of 
a  unit  element  in  view  of  the  results  of  recent  researches  in 
physics  respecting  atomic  structure,  experiments  con- 
cerning radio-activity  having  demonstrated  the  transference 
of  the  apparently  distinct  substances  or  chemical  entities 
into  others.  Accordingly,  it  is  conjectured  that  atoms 
consist  of  positively  charged  nuclei  surrounded  at  a  distance 
by  distributed  electrons  or  charges  of  electricity,  the  normal 
(atomic)  number  being  equal  to  the  number  of  unit  positive 
charges  in  the  nucleus  which  makes  them  electrically 
neutral.  The  nuclei  are  supposed  to  contain  the  mass  of 
the  atoms  although  of  exceedingly  small  dimensions,  the 
diameter  being  of  the  order  of  o-ooooi  of  that  of  the  atom, 
and  the  region  occupied  by  the  external  electrons  very  large 
in  comparison.  Viewed  thus,  the  nuclear  charge  of  the 
hydrogen  atom  is  one  unit  of  electricity,  that  of  helium  two 
charges,  and  so  forth  up  to  uranium  (the  heaviest  atom) 
with  a  charge  of  92  units.  It  is  obvious  that  subject  to 
this  hypothesis,  electricity  is  endowed  with  the  properties  of 
matter,  and  the  so-called  elements  therefore  as  systems  of 
electricity,  differing  in  the  number  of  electrons  and  in  their 
motion  relative  to  each  other.  Further,  it  is  supposed 
that  if  the  number  of  electrons  in  the  atom  exceeds  the 
atomic  number,  it  is  a  negatively  charged  atom  or  ion, 
while,  reversely,  the  atom  is  positively  charged. 

From  a  recent  study  of  the  deflection  of  particles  liberated 
from  atmospheric  nitrogen  under  certain  conditions,  it  has 
been  concluded  that  hydrogen  is  one  of  the  products  of  the 
disintegration  of  the  nitrogen  atom. 

The  problem  of  the  essential  constitution  of  atomic 
matter  must,  however,  be  regarded  as  at  present  pro- 
blematical. (See  Elements,  Matter,  and  Radio-activity.) 

ATOMIC  VOLUME— The  atomic  volume  of  an  element  is  the 
atomic  weight  divided  by  its  specific  gravity. 

ATOMIC  WEIGHTS— The  atomic  weights  ordinarily  adopted 
are  those  expressed  in  relation  to  hydrogen  as  the  unit, 
but  in  the  following  table  they  are  also  given  in  relation  to 
oxygen,  taken  as  the  standard  of  comparison  (16),  the 
atomic  weight  of  hydrogen  then  becoming  roo8.  These 
international  weights  are  revised  yearly  in  the  light  of  the 


44  INTERNATIONAL  ATOMIC  WEIGHTS 

ATOMIC  WEIGHTS,   1921. 


*i 

Jj 

"I 

* 

II 
K 

! 

II 
1* 

•2  12 
f| 
M 

3 

|i 

II 

U  y 

>, 

£  o 

O   V 

>, 

C     y 

Is 

CO 

Si 

C   o 

'§£ 

CO 

c'l 

1* 

~< 

IJ, 

""  <5 

w 

X 

Aluminium 

27 

Al 

27-1 

Neon 

20 

Ne 

2O  2 

Antimony    ... 

120 

Sb 

1  2O  '2 

Nickel 

59 

Ni 

58-68 

Argon 

40 

A 

39  '9 

Niton  (radium 

Arsenic 

75 

As 

74-96 

emanation) 

Nt 

222'4 

Barium 

137 

Ba 

137*37 

Nitrogen 

14 

N 

14-008 

Bismuth 

208 

Bi 

208*0 

Osmium 

191 

Os 

I90-9 

Boron 

ii 

B 

10-9 

Oxygen 

16 

0 

16-0 

Bromine 

80 

Br 

79-92 

Palladium  ... 

106 

Pd 

106-7 

Cadmium    ... 

112 

Cd 

112-4 

Phosphorus 

3i 

P 

31-04 

Caesium 

133 

Cs 

132-81 

Platinum    ... 

*95 

Pt 

195-2 

Calcium 

40 

Ca 

40-07 

Potassium  ... 

39 

K 

39*i 

Carbon 

12 

C 

12-005 

Praseody- 

Cerium 

140 

Ce 

140-25 

mium 

I40'5 

Pr 

140-9 

Chlorine 

35'5 

Cl 

35-46 

Radium 

226-4 

Ra 

226-0 

Chromium  ... 

52 

Cr 

52-0 

Rhodium     ... 

103 

Rh 

102-9 

Cobalt 

59 

Co 

58-97 

Rubidium   ... 

85 

Rb 

85-45 

Columbium 

93-i 

Cb 

93'i 

Ruthenium 

ioi'7 

Ru 

101-7 

Copper 

63-5 

Cu 

63'57 

Samarium  ... 

150 

Sa 

150-4 

Dysprosium 

Dy 

162-5 

Scandium   ... 

44 

Sc 

45*i 

Erbium 

1  66 

Er 

167-7 

Selenium    ... 

79 

Se 

79*2 

Europium  ... 

Eu 

152-0 

Silicon 

28 

Si 

28-3 

Fluorine 

19 

F 

19-0 

Silver 

108 

Ag 

107-88 

Gadolinium 

Gd 

i57'3 

Sodium 

23 

Na 

23-0 

Gallium 

70 

Ga 

70-1 

Strontium  ... 

87-6 

Sr 

87-63 

Germanium 

72 

Ge 

72-5 

Sulphur 

32 

S 

32-06 

Glucinum    ... 

Gl 

9-1 

Tantalum    ... 

181 

Ta 

181-5 

Gold 

197 

Au 

197-2 

Tellurium  ... 

127 

Te 

127-5 

Helium 

4 

He 

4-0 

Terbium 

Tb 

159-2 

Holmium    ... 

Ho 

163-5 

Thallium     ... 

204 

Tl 

204*0 

Hydrogen  ... 

i 

H 

i  -008 

Thorium 

232 

Th 

232-15 

Indium 

"5 

In 

114-8 

Thulium     ... 

Tm 

168-5 

Iodine 

127 

I 

126-92 

Tin  

118 

Sn 

118-7 

Iridium 

193 

Ir 

193-1 

Titanium    ... 

48 

Ti 

48-1 

Iron... 

56 

Fe 

55-84 

Tungsten    ... 

184 

W 

184-0 

Krypton 

83 

Kr 

82-92 

Uranium     ... 

238-5 

u 

238-2 

Lanthanum 

139 

La 

139-0 

Vanadium  ... 

5i 

V 

51-0 

Lead 

207 

Pb 

207-2 

Xenon 

130 

Xe 

130-2 

Lithium 

7 

Li 

6-94 

Ytterbium 

Lutecium    ... 

Lu 

175-0 

(Neo  ytter- 

Magnesium 

24 

Mg 

24-32 

bium) 

172 

Yb 

i73'5 

Manganese 

55 

Mn 

54*93 

Yttrium 

89 

Yt 

88-33 

Mercury 

200 

Hg 

200-6 

Zinc  ... 

65 

Zn 

6537 

Molybdenum 

96 

Mo 

96-0 

Zirconium  ... 

907 

Zr 

90-6 

Neodymium 

144 

Nd 

J44*3 

ATOMIC  WEIGHTS— A  URINE  45 

ATOMIC  WEIGHTS  (Continued)— 

most  recent  investigations.  The  atomic  weights  may  be 
connected  by  precise  mathematical  equations,  but  if  so  the 
nature  of  these  relationships  have  not  yet  been  discovered. 
(See  Table  on  p.  44.) 

ATROPINE  (C17H23NO3)  is  a  highly  poisonous  organic  base 
or  alkaloid,  isomeric  with  hyoscyamine,  prepared  from 
Atropa  belladonna  (*'  deadly  nightshade  "),  both  of  which  are 
remarkable  for  their  power  of  dilating  the  pupil  of  the 
eye.  It  crystallizes  in  colourless  prisms  or  needles,  which 
melt  at  114°  to  115°  C.,  and  is  soluble  in  water,  alcohol, 
and  ether.  Belladonna  leaves  should  contain  a  total  quantity 
of  about  0*4  per  cent,  alkaloids.  Preparations  of  bella- 
donna are  used  in  medicine  in  the  form  of  tinctures, 
extracts,  and  plasters  to  check  excessive  secretion  and  to 
allay  inflammation.  (See  Belladonna  Oil.) 

ATTAR  OF  ROSES  (otto  of  roses)  is  obtained  by  distilling 
the  fresh  flowers  of  Rosa  damascena  with  water,  and  is  made 
in  Bulgaria,  France,  Turkey,  Persia,  and  India,  3  drachms 
being  obtained  from  100  pounds  of  the  flower-petals.  The 
distilled  oil  is  pale  yellow,  and  has  a  sp.  gr.  of  0*853  *° 
0*862.  Its  refractive  index  is  1*460  to  1*465,  and  rotation 
-  2°  to  -  4°.  It  contains  from  70  to  75  per  cent,  of  its 
odourous  constituents — namely,  geraniol  and  citronellal. 
It  also  contains  an  odourless  substance  (stearoptene)  to  the 
extent  of  from  10  to  16  per  cent.,  consisting  of  a  mixture  of 
two  hydrocarbons  insoluble  in  alcohol,  and  which  can  be 
frozen  out  by  cooling  the  oil  below  18°  C.  The  odoriferous 
constituents  of  the  oil  are  soluble  in  alcohol.  Otto  of  roses 
is  frequently  adulterated  with  geranium  oil.  It  is  chiefly 
used  in  perfumery  and  for  flavouring. 

ATTENUATION — A  term  used  by  bacteriologists  to  signify 
the  weakening  of  bacterial  life,  and  by  brewers  to  signify 
the  weakening  of  worts  by  fermentation  of  the  contained 
sugars.  The  same  term  is  used  by  chemists  to  signify  the 
rarefication  or  thinning  of  gaseous  bodies.  (See  Vacuum.) 

ATTRACTION— See  Chemical  Attraction. 

AUBEPINE— anisic  aldehyde  (C8H8O2) — A  colourless  liquid  of 
aromatic  odour,  soluble  in  alcohol  and  ether,  and  used  in 
perfumery. 

AURIFEROUS — A  term  applied  to  ores  or  minerals  containing 

gold. 
AURINE  (C19H14O3)— A  dye  which  crystallizes  in  beautiful 

green  needles  and  prisms  of  a  metallic  lustre,  and  can  be 


46  A  URINE—  B  A  CTERIA 

AURINE  (Continued)  — 

made  by  heating  phenol  with  a  mixture  of  sulphuric  and 
oxalic  acids  to  a  temperature  of  from  130°  to  150°  C.  Its 
constitution  is  shown  by  the  structural  formula  : 

CeH4OH 


AUTOCLAVES  —  Apparatus  for  maintaining  liquids  at  any 
desired  temperatures  and  pressures  in  chemical  labora- 
tories, and  constituting  an  important  part  of  the  plant  used 
in  chemical  industry. 

AVOGADRO'S  LAW—  See  Molecules. 

AZO-DYES  —  A  large  class  of  dyes  containing  one  or  more 
so-called  azo  groups  -  N  :  N  —  linking  together  aromatic 
radicles.  Many  of  them  dye  cotton  without  the  use  of  a 
mordant,  whilst  others  act  as  very  fast  mordant  dyes  on 
wool.  They  may  be  regarded  as  originating  from  the  red 
crystalline  parent  substance,  azobenzene,  C6H5:  N  :N.C6H5, 
all  its  basic  and  acid  derivatives  being  colouring  matters. 

Azobenzene  itself  is  obtained  from  nitrobenzene  by 
reduction  of  a  solution  of  that  substance  in  ether  containing 
water  by  means  of  sodium  amalgam. 

These  groups  of  atoms,  such  as  —  N:N—  or  -  N  =  N  —  , 
are  known  as  chromophors,  and  produce  dyes  when  intro- 
duced into  so-called  chvomogens  or  compounds  which  contain 
unsaturated  groups  of  C6  arranged  as  in  benzene. 

AZURITE—  A  blue  basic  copper  carbonate  (2CuCO3,Cu(HO)2) 
found  in  the  native  state  at  Chessy,  near  Lyons,  the  United 
States  of  America,  and  elsewhere  ;  also  known  as  chessylite. 
(See  Copper.) 

BACTERIA  are  microscopic  organisms  of  which  the  largest  is 
less  than  -^  of  an  inch  in  length,  while  some  of  them 
require  to  be  magnified  thousands  of  times  to  become 
visible.  They  abound  universally  and  constitute  the 
simplest  and  lowest  known  forms  of  life.  They,  or 
some  of  them,  are  the  indirect  causes  of  certain  infectious 
diseases,  and  they  are  capable  of  inciting  many  chemical 
changes  in  the  nature  of  fermentations,  oxidation,  and 
hydrolysis.  The  souring  of  milk  is  caused  by  the  Bacterium 
lactis,  that  of  dilute  wine  by  the  Mycoderma  aceti,  etc.  Most 
bacteria  are  destroyed  when  heated  for  a  short  time  to  the 
temperature  of  boiling  water  (100°  C.),  particularly  in  the 
presence  of  moisture,  and  all  of  them  after  a  prolonged 
exposure.  They  are  also  readily  destroyed  by  a  number  of 


BACTERIA— BALSAMS  47 

BACTERIA  (Continued)— 

chemical  agents,  including  a  solution  of  corrosive  sublimate 
(i  in  1,000),  exposure  to  formaldehyde  in  liquid  or  vaporous 
form  of  sufficient  strength,  or  to  the  vapour  of  sulphur 
dioxide  as  generated  by  burning  sulphur  candles  (particu- 
larly when  in  association  with  water  vapour),  and  by  many 
disinfectant  preparations. 

Many  kinds  develop  by  spore-bearing,  and  the  spores  are 
usually  more  difficult  to  kill  than  the  fully  developed  germs. 

The  activities  of  bacteria  are  not  confined  to  organic 
compounds,  many  changes  affecting  the  earth's  surface 
being  due  in  part  to  biological  influences  in  which  these 
micro-organisms  participate.  Various  iron  compounds,  for 
example,  came  within  their  influence,  ferric  hydroxide 
being  precipitated  from  solutions  of  ferrous  bicarbonate 
by  the  action  of  a  group  of  bacteria,  and  they  are  regarded 
as  factors  in  the  natural  production  of  many  deposits  of 
ferruginous  sedimentary  ores.  Sulphuretted  hydrogen 
results  as  a  product  of  decomposition  of  animal  and  vege- 
table matters  by  saprophytic  bacteria,  and  this,  by  action 
on  iron  compounds,  is  supposed  to  be  connected  with  the 
formation  of  the  "  blue  mud  "  of  the  ocean  bottoms.  (See 
also  Nitrification.) 

"  BACTEROL  " — A  proprietary  antiseptic  containing  formalde- 
hyde associated  with  small  proportions  of  other  substances. 

"  BACTOX " — A  powerful  proprietary  antiseptic  and  dis- 
infectant made  from  certain  phenoloids  in  a  form  miscible 
with  water. 

"  BAKELITE  " — The  trade  name  of  a  black  material  made  from 
phenol  by  the  action  of  formaldehyde,  used  as  a  plastic, 
and  for  insulating  purposes. 

BAKING-POWDERS — Preparations  used  as  substitutes  for 
yeast  in  making  bread  spongy  in  character  by  the  pro- 
duction of  carbon  dioxide  in  the  dough.  The  joint  use  of 
tartaric  acid  and  sodium  bicarbonate  will  produce  such  a 
result  for  example. 

BALATA — The  rubber  gum,  or  coagulated  latex  of  Mimusops 
globosa — a  forest  tree  of  the  order  Sapotacece,  which  grows 
in  Guiana  and  elsewhere,  known  otherwise  as  the  "  bully 
tree."  It  resembles  gutta-percha  in  nature  and  properties, 
and  finds  many  similar  commercial  applications. 

BALSAMS  are  natural  products  consisting  of  essential  or 
volatile  oils  admixed  with  resins  which  are  supposed  to  be 
derived  from  the  oils  by  atmospheric  oxidation. 


48  BALSAMS 

BALSAMS  (Continued)— 

Copaiba  Balsam  is  produced  by  several  varieties  of  Copaifera 
indigenous  in  Brazil,  Peru,  Mexico,  and  the  Antilles.  It  flows 
from  incisions  made  for  that  purpose  in  the  trees  during  rainy 
weather,  and  in  this  form  it  is  a  syrupy,  oily  liquid  varying 
in  character  and  properties  according  to  the  species  of  trees 
from  which  it  is  obtained.  By  exposure  to  the  air  it 
becomes  solid  and  is  used  not  only  in  medicine  but  also  in 
preparing  lac  varnishes  and  tracing  paper.  It  is  soluble  in 
alcohol,  ether,  chloroform,  benzol,  and  carbon  disulphide, 
and  has  a  sp.  gr.  0*940  to  0*990. 

Mecca  Balsam  or  Balm  of  Gilead  is  the  produce  of  the 
Balsamodendron  gileadense,  a  terebinthaceous  shrub,  native  of 
Arabia  Felix.  There  are  several  varieties  and  the  finest 
quality  of  fragrant  odour  is  said  to  exude  from  the  flowers, 
whilst  an  inferior  quality  is  obtained  from  incisions  in  the 
branches.  It  is  not  much  used  in  medicine  now,  but  in  the 
East  it  is  used  as  a  tonic. 

Peru  Balsams  are  of  three  varieties  (white,  dry  and  black), 
sp.  gr.  1*14  to  1*15  ;  soluble  in  alcohol  and  ether. 

Storax  ^Balsam  (Oriental  sweet  gum)  is  the  produce  of 
Sty  rax  officinalis  (a  shrub  growing  in  the  Levant,  Palestine, 
Syria  and  Greece).  This  is  known  in  two  varieties — viz., 
liquid  and  solid  forms,  soluble  in  ether  and  hot  alcohol, 
and  is  used  in  medicine  as  a  stimulating  expectorant,  in 
perfumery,  and  as  a  detergent  in  the  form  of  ointment. 
The  semi-liquid  balsam  from  Liquidambav  orientate,  known 
in  the  U.S.A.  as  "sweet  gum,"  contains  over  28  per  cent. 
cinnamic  acid  (C9H8O2),  a  substance  which,  when  fused 
with  potash,  splits  up  into  benzoic  and  acetic  acids. 

The  American  storax  is  derived  from  Liquidambar  styraxi- 
flora,  found  in  great  forests  high  up  in  the  mountains  of 
Honduras. 

Tolu  Balsam,  a  nearly  solid,  resinous  mass  of  aromatic 
odour  used  in  medicine ;  is  obtained  in  large  quantities 
from  Myrospermum  toluiferum,  growing  in  various  parts  of 
Columbia  and  South  America.  It  contains  benzoic  and 
cinnamic  acids. 

Canada  Balsam  or  Canadian  Turpentine  is  produced  by 
Abies  balsamea,  a  conifer  which  grows  in  Canada,  Virginia, 
Carolina,  and,  like  all  the  turpentines,  is  produced  by 
making  incisions  in  the  stem.  So  also  in  common  with 
other  crude  turpentines,  when  distilled  it  yields  turpentine 
oil  and  leaves  resin  behind  in  the  retorts,  It  is  a  yellowish 


BALSAMS— BARIUM  49 

BALSAMS  (Continued)— 

viscid  liquid,  of  pleasant,  pure  odour  and  bitter  taste,  soluble 
in  ether,  chloroform-,  benzol,  etc.  (See  Gums  and  Essential 
Oils.) 

BAEBARY  GUM — The  product  of  the  African  Acacia  gummif era. 

BAEBEY  IXOMETEE — An  apparatus  for  determining  the 
fluidity  of  oils  by  the  rate  of  flow.  It  is  so  constructed  that 
a  pressure  of  100  millimetres  of  liquid  is  kept  at  a  fixed 
temperature  of  35°  C. 

Raw  colza  oil  freshly  prepared  and  drawn  off  marks 
exactly  100°  of  fluidity  by  this  apparatus. 

BAEBITONE  (C2H5)2.C(CONH)2CO) —  Another  name  for 
veronal  (diethylbafbituric  acid),  a  white  crystalline  body, 
soluble  in  water,  which  is  used  as  a  soporific;  melting- 
point  182°  C. 

BAEIUM  (Ba)  and  its  compounds — Barium  is  a  yellow, 
lustrous  metal  of  malleable  character,  having  an  atomic 
weight,  137 ;  sp.  gr.,  3-78 ;  and  melting-point,  850°  C. 
Barium  sulphate  (BaSO4)  is  abundantly  found  in  nature 
in  the  forms  of  heavy  spar  or  barytes  (in  the  metalliferous 
mines  of  Durham,  Cumberland,  and  Westmorland,  and  in 
the  secondary  limestone  in  many  places),  and  barium  car- 
bonate (BaCO3)  occurs  as  witherite.  The  home  output  of 
barium  minerals  in  1918  amounted  to  66,360  tons. 

Barium  Chloride  (BaCl22H2O),  a  colourless,  crystalline 
salt,  is  obtained  by  dissolving  the  native  carbonate  in 
hydrochloric  acid  and  crystallizing  it  out  of  solution  when 
it  forms  rhombic  tables,  which  are  very  soluble  in  water.  It 
is  used  in  the  leather  industry,  as  a  rat  poison,  and  in  making 
boiler  compounds.  When  barium  chloride  in  solution  is 
mixed  with  a  dilute  solution  of  sulphuric  acid  (H2SO4), 
barium  sulphate  is  precipitated  in  an  insoluble  form — 

BaCl2  +  H2S04=  BaS04  +  2HC1. 

Barytes,  in  the  forms  of  finely  ground  heavy  spar,  as  also  the 
precipitated  sulphate,  are  both  used  in  compounding  several 
distinct  pigments,  including  permanent  white  and  blanc  fixe, 
and  for  admixture  with  white  lead  in  paint-making. 

Barium  Nitrate  (Ba(NO3)2)  is  obtained  by  dissolving 
witherite  in  dilute  nitric  acid.  It  crystallizes  in  large 
colourless  octahedra  and  is  soluble  in  water,  but  not  so 
soluble  as  the  chloride,  and  is  used  in  pyrotechnics  for 
making  green  fire. 

4 


50  BARIUM 

BARIUM  (Continued]— 

Barium  Sulphide  (BaS),  a  yellowish-green  substance, 
soluble  in  water,  is  sometimes  used  as  a  luminous  paint, 
as  it  possesses,  in  common  with  calcium  sulphide  (CaS), 
the  property  of  emitting  a  feeble  phosphorescent  light  in 
the  dark.  It  is  also  used  as  a  depilatory,  in  vulcanizing, 
and  for  weighting  gutta-percha.  It  is  prepared  from  barium 
compounds  by  methods  similar  to  those  used  in  the  pre- 
paration of  the  corresponding  calcium  sulphide. 

There  are  two  oxides  of  barium — white  insoluble  bodies 
— viz.,  the  monoxide  (BaO)  and  dioxide  (BaO2),  the  last- 
named  of  which  is  used  in  the  manufacture  of  hydrogen 
dioxide.  When  the  monoxide  is  slaked  with  water  it  gives 
rise  to  the  formation  of  a  hydrate  or  hydroxide  (BaH2O2) 
which  is  fairly  soluble  in  hot  water  and  can  be  obtained  in 
a  crystalline  form. 

Barium  Acetate  (Ba(C2H3O2)2H2O)— A  white  crystalline 
salt,  soluble  in  water. 

Barium  Carbonate  (BaCO3) — A  white  compound,  in- 
soluble in  water,  used  in  ceramics,  and  in  the  form  of  a 
paste,  regarded  as  one  of  the  most  effective  poisons  for 
rats.  A  mixture,  largely  used  in  India,  is  prepared  from : 

Barium  carbonate  ...         ...  6  ounces. 

Common  salt     ...  ...         ...  \  ounce. 

Wheat  flour       ...  ...         ...  4  ounces. 

Pea  or  bajri  flour  ...         ...  12      „ 

Dripping  or  ghee  4      „ 

This  quantity  is  sufficient  for  1,000  baits.     The  dripping 
or  ghee  is  melted,  and  the  whole  mixture  worked  into  a 
paste  or  dough,  rolled  out,  and  cut  up  into  small  squares. 
Other  barium  compounds  are  as  follows : 

Barium  Chlorate  (Ba(ClO3)2,H2O)— White,  crystalline, 
soluble  in  water,  and  used  in  pyrotechnics  and  dyeing. 

Barium  Chromate  (BaCrO4) — A  heavy,  yellow,  crystalline 
body,  insoluble  in  water,  and  used  in  compounding  pig- 
ments and  making  safety  matches. 

Barium  Cyanide  (Ba(CN)2)— White,  crystalline,  and 
soluble  in  water  and  alcohol ;  used  in  metallurgy. 

Barium  Fluoride  (BaF2) — A  white  powder,  used  in 
enamel-making. 

All  the  soluble  salts  of  barium  are  poisonous. 


BARK— BASALT  51 

BARK — The  outer  rind  of  trees,  the  principal  ones  being  the 
cork-bark  (see  Cork),  the  oak  bark  used  in  tanning,  and  the 
Peruvian  bark  from  which  quinine,  etc.,  is  prepared. 

BARM — The  yeasty  top  which  forms  on  fermenting  beer,  used 
as  leaven  in  bread-making  and  for  other  fermentations. 
(See  Yeasts.) 

BAROMETERS — Instruments  devised  for  indicating  the  pres- 
sure and  density  of  the  air.  They  are  made  in  various 
forms,  of  which  the  simplest  consists  of  a  straight  glass 
tube  closed  at  one  end,  filled  with  mercury  and  inverted 
with  the  open  end  in  a  tray  of  mercury.  It  is  gene- 
rally assumed  that  the  average  ordinary  density  of  the 
air  is  when,  at  sea-level  and  at  a  temperature  of  zero 
(o°  C.),  the  column  of  mercury  in  the  tube  stands  at 
760  millimetres,  or  29^92  inches  high.  As  the  pressure  or 
density  of  the  atmosphere  increases,  the  column  rises,  and 
as  it  diminishes  the  column  falls.  The  normal  pressure  is 
about  147  pounds  to  the  square  inch. 

The  space  above  the  mercury,  in  the  simplest  form  of  a 
mercurial  barometer,  is  practically  vacuous,  and  is  popularly 
known  as  the  Torricellian  vacuum. 

As  the  barometer  measures  the  weight  of  the  super- 
incumbent air,  it  necessarily  follows  that  the  higher  the 
altitude  the  lower  the  barometer  indication.  In  chemical 
investigations,  gases  are  weighed  or  measured  subject  to 
the  atmospheric  pressure,  and  vary  directly  in  density  and 
inversely  in  volume  with  the  pressure  ;  hence  the  necessity 
of  recording  the  pressure  and  reducing  the  amount  to  a 
standard  pressure,  as  also  a  standard  temperature.  (See 
Attenuation  and  Vacuum.) 

BARRILLA — An  impure  sodium  carbonate,  somewhat  like 
kelp,  produced  in  Spain  and  the  Levant  by  burning  certain 
plants  to  ashes.  These  plants  grow  on  the  seashore  and 
belong  chiefly  to  the  genus  Salsola. 

BARWOOD  (Camwood) — An  African  red  dye  wood  from  the 
Baphita  nitida,  which  contains  23  per  cent,  of  red  colouring 
matter  soluble  in  hot  alcohol,  supposed  to  be  identical  with 
"  santalin  "  (a  crystalline  red  body  obtained  from  sandal  wood). 

BARYTES  (Heavy  Spar)— See  Barium. 

BARYTOCALCITE  —  A  mineral  compound  carbonate  of 
barium  and  calcium  of  the  composition  BaCO3,CaCO3. 

BASALT — A  dark-coloured  form  of  felspar. 


52  BASES  (ALKALIES) 

BASES  (ALKALIES) — Bodies  which  combine  with  acids, 
thereby  neutralizing  their  acidity,  and  forming  salts. 
Originally,  the  compound  known  as  potassium  carbonate 
was  obtained  from  the  ashes  of  seaweed  and  was  called 
alkali,  a  word  of  Arabic  origin.  By  the  term  alkali  is  now 
meant  something  of  exactly  the  opposite  nature  to  acid. 
The  common  alkalies  are  named  potash,  soda,  and  ammonia. 

Potash  (or  potassium  hydrate)  is  a  combination  of  i  atom 
potassium,  i  atom  hydrogen,  and  i  atom  oxygen — KHO. 

Potassium  carbonate  is  a  combination  of  2  atoms  potas- 
sium, i  atom  carbon,  and  3  atoms  oxygen — K2CO3. 

Soda  (or  sodium  hydrate)  is  a  combination  of  i  atom 
sodium  with  i  atom  hydrogen  and  i  atom  oxygen — NaHO, 
and  sodium  carbonate  (the  essential  constituent  of  common 
washing-soda)  is  Na2CO3. 

Potassium  and  sodium  in  combination  with  oxygen  alone 
form  oxides,  and  their  formulae  are  as  follows :  K2O  and 
Na2O.  It  is  by  combination  of  these  oxides  with  water 
that  the  respective  hydrates  (or,  as  they  are  alternatively 
called,  hydroxides)  are  formed.  For  example,  a  molecule 
of  the  potassium  oxide  combining  with  a  molecule  of  water 
gives  2  molecules  of  potassium  hydrate,  thus  : 

K2O  +  H2O  =  2KHO. 

Ammonium  hydrate  is  a  combination  of  i  atom  nitrogen, 
5  atoms  hydrogen,  and  i  atom  oxygen — NH4HO. 

These  oxides  and  hydrates  are  all  soluble  in  water. 

Barium  oxide  (BaO),  when  combined  with  water,  forms 
barium  hydrate  as  follows : 

BaO  +  H2O  =  BaH202. 

In  this  case,  i  part  or  molecule  of  the  barium  oxide  (which 
is  insoluble  in  water)  enters  into  combination  with  i  part 
or  molecule  of  water,  and  produces  i  part  or  molecule  of 
barium  hydrate  (which  is  soluble  in  water  to  some  extent). 
A  hydrate  is  therefore  a  combination  of  an  oxide  of  a  base 
or  metal  and  the  elements  of  water. 

These  alkaline  bodies  are  all  more  or  less  soapy  to  the 
feel  when  dissolved  in  water,  and  they  have  the  opposite 
action  on  colours  to  acids — that  is,  they  turn  vegetable  red 
colours  to  blue  colours. 

They  are  also  classified  as  bases;  but  there  are  many 
other  kinds  of  bases,  all  of  which  have  the  property  of 
entering  into  chemical  action  with  acids  to  form  compounds 
which  are  called  salts,  including  all^those  organic  bodies 


BASES  (ALKALIES)— BAY    OIL  53 

BASES  (ALKALIES)  (Continued)— 

which  are  derivatives  of  ammonia  or  may  be  viewed  as  such, 
including  the  amines  and  the  alkaloids. 

The  same  term  is  used  to  include  the  derivative  com- 
pounds of  the  phosphorus,  arsenic  and  antimony  analogues 
of  ammonia;  the  phosphines,  arsines  and  stibines  being  de- 
rived by  the  exchange  of  hydrogen  for  radical  groups  such 
as  CH3  and  C2H5  in  the  compounds  known  as  phosphor- 
etted  hydrogen,  arseniuretted  hydrogen  and  antimoniuretted 
hydrogen  respectively ;  so  that  there  result  for  examples 
triethyl  phosphine,  P(C2HJ3,  trimethyl  arsine,  P(CH3)3, 
and  trimethyl  stibine,  Sb(CH3)3,  all  of  which  are  of  more 
or  less  basic  character. 

BASIC  SLAG— See  Iron  and  Slag. 

BASSIA  OIL  (AND  FATS)— Obtained  from  trees  of  the  Bassia 
species  which  grow  in  India  and  the  East  Indies,  including 
"  Mowrah  seed  oil,"  "  Illipe  butter,"  "  Shea  butter,"  "  Njave 
oil,"  etc.  (See  Shea  Butter.) 

BASSORA  GUM — From  the  Acacia  leucophlaa. 

BASSWOOD  (LINDEN)  OIL — From  Tilia  americana,  like  cotton- 
seed oil,  containing  glycerides  rich  in  butyric  acid. 

BATHBRICK — Scouring  bricks  made  of  calcareous  and  siliceous 
earth  obtained  from  deposits  at  Bridgwater  and  other 
places. 

BATHSTONE — A  natural  formation  of  rock  chiefly  composed 
of  calcium  carbonate,  and  largely  employed  in  the  con- 
struction of  buildings. 

BATTERIES  (Storage)— See  Electricity. 
BATTERIES  (Electrical)— See  Electricity. 
BATTERY — A  stamping  mill  used  in  mining. 

BAUXITE — Natural  hydrated  aluminium  oxide  (A12O32H2O). 
There  are  several  varieties  of  this  mineral — viz.,  a  white 
quality  containing  some  60  per  cent,  alumina,  a  little  iron, 
and  no  silica,  which  is  used  for  making  aluminium  salts 
and  alum  ;  a  red  variety  of  about  the  same  alumina  content 
but  containing  little  silica,  used  for  manufacturing  metallic 
aluminium ;  and  another  white  kind  containing  only  45  per 
cent,  alumina  and  much  silica,  which  is  used  more  for 
making  refractories.  (See  Aluminium.) 

BAY  OIL  (Myrcia  oil) — A  yellowish  essential  oil  distilled  from 
the  leaves  of  Myrcia  acris,  of  sp.  gr.  0*965  to  0-995.  The 
yield  is  from  2  to  3  per  cent.,  and  the  oil  is  used  in 


54  BAY  OIL— BEER 

BAY  OIL  (Continued)— 

perfumery  and  for  making  bay-rum.     It  contains  terpenes 
and  eugenol. 

BAY-BERRY  WAX— See  Waxes. 

BAY  SALT  is  produced  by  the  evaporation  of  sea- water. 

BEAKERS  are  thin  glass  vessels  made  of  such  a  quality  as  to 
withstand  exposure  to  heat,  cylindrical  in  shape  with  flat 
bottoms,  and  are  sometimes  provided  with  a  lip  to  facilitate 
the  transfer  of  contents.  They  are  of  various  sizes,  from 
quite  small  ones  up  to  a  capacity  of  a  litre  (1,000  c.c.)  and 
more ;  and  are  not  only  used  for  holding  and  heating 
liquids,  but  also  for  effecting  many  chemical  operations. 

BEECHWOOD  CREOSOTE  —  A  colourless  or  faintly  yellow 
creosotic  liquid  obtained  from  the  tar  resulting  from  the 
distillation  of  beechwood,  and  containing,  amongst  other 
phenolic  constituents,  an  active  liquid  named  creosol 
(C8H10O2),  which  boils  at  220°  C.  It  is  soluble  in  alcohol 
and  ether,  and  to  some  extent  in  water;  sp.  gr.,  1-080; 
boiling-point,  2O5°-22o°  C.  It  is  preferably  prepared  from 
Fagus  sylvatica  or  F.  fermginea. 

BEER — Infusion  of  malt,  flavoured  with  the  bitter  of  hops 
and  fermented  with  yeast,  containing  from  2  to  6  per  cent, 
of  alcohol.  Porter  and  stout  are  beers,  owing  their  dark 
colour  and  special  flavour  to  the  employment  of  added 
colouring  matters  or  "  high  dried  "  malt.  Any  farinaceous 
grain  can  be  used,  but  barley  is  generally  preferred.  It  is 
allowed  to  germinate,  and  is  subsequently  kiln-dried,  con- 
verting it  thereby  into  malt,  and  the  higher  the  temperature 
at  which  it  is  dried  the  darker  becomes  the  colour.  By  the 
process  of  germination,  diastase  is  formed  from  the  albumi- 
noid part  of  the  grain,  and  the  starch  is  converted  by  the 
diastase  into  dextrin  and  sugar,  which  in  their  turn  are 
converted  into  alcohol  by  the  subsequent  fermentation 
with  yeast.  This,  however,  is  not  allowed  to  proceed  to 
completion,  so  that  some  sugar  may  be  left  in  solution  after 
the  fermented  wort  is  separated  from  the  yeast.  The 
strength  and  flavour  of  the  beer  admit  of  endless  variation, 
strong  beers  containing  more  alcohol  than  mild  ales,  and 
substantial  ones  having  more  "body"  —  that  is,  being 
richer  in  malt  extract. 

In  brewing,  the  character  of  the  water  is  of  great  im- 
portance, and  it  may  be  said  that  the  purer  it  is  the  better  : 
hard  waters,  however,  can  be  used  in  making  pale  ales,  but 
soft  waters  are  better  for  stouts  and  porter. 


BEER— BELL-METAL  55 

BEER  (Continued) — 

While  by  the  action  of  enzymes,  a  certain  amount  of 
ready-formed  soluble  carbohydrates  are  formed  during  the 
malting  process,  it  is  in  the  mash  tun  that  diastase  exercises 
its  fuller  function  of  saccharifying  the  starch  of  the  malt — 
sometimes  supplemented  by  the  addition  of  other  starchy 
substances,  such  as  maize,  rice,  barley — into  dextrin,  malto- 
dextrin,  and  maltose.  When  starchy  bodies  are  added  as 
mentioned,  they  are  first  of  all  gelatinized  by  heating  with 
or  without  a  little  malt,  in  an  apparatus  styled  a  converter, 
thus  facilitating  the  action  of  the  diastase. 

The  purity  (cultivation)  of  the  yeast  is  of  great  importance, 
and  much  more  care  is  taken  now  than  in  former  years  in 
scientific  brewing  to  prepare  purer  cultures,  so  as  to  avoid 
the  presence  in  the  beer  of  those  undesirable  products 
which  are  produced  by  otherwise  associated  ferments, 
(See  Malt.) 

BEESWAX— See  Waxes. 

BEET-SUGAR  (C12H22On)— Sugar  extracted  from  beet-roots, 
which  contains  from  14  to  18  per  cent,  of  cane  sugar.  (See 
Sugar.) 

BECQUEREL  RAYS— A  study  of  the  radiations  emitted  by 
phosphorescent  bodies  led  Becquerel  to  the  discovery  that 
certain  salts  of  uranium  evolve  rays  which  possess  the 
property  of  affecting  a  photographic  plate,  and  that  of 
rendering  the  surrounding  medium  an  electrical  conductor. 
These  rays,  like  the  cathode  rays,  travel  in  straight  lines 
and  can  traverse  wood,  paper,  and  some  metals,  including 
aluminium.  (See  Radio-activity.) 

BEGKASSE — The  waste  pulp  left  after  expressing  sugar  from 
sugar-canes,  which  finds  use  as  a  fuel. 

BELLADONNA  OIL  is  expressed  in  Wurtemberg  from  the 
seeds  of  Atropa  belladonna,  and  used  for  illumination  and 
other  purposes.  The  poisonous  principle  is  said  to  be 
retained  in  the  marc,  which  therefore  cannot  be  used  as 
cattle  food.  (See  Atropine.) 

BELLITE— See  Explosives. 

BELL- JAR — A  glass  jar  of  bell  shape  used  for  covering  other 
vessels  and  for  other  purposes.  (See  Desiccator.) 

BELL-METAL — An  alloy  of  about  77  per  cent,  copper  arid, 
23  per  cent.  tin.  (See  Alloys.) 


56  BENGAL  FIRE— BENZINE 

BENGAL  FIRE — A  mixture  of  realgar  (arsenic  disulphide), 
sulphur,  and  nitre. 

BENZALDEHYDE  (C7H6O  or  C6H5CHO)  — A  colourless 
liquid  of  high  refractive  character  and  almond-like  odour, 
soluble  in  alcohol  and  ether,  having  a  sp.  gr.  of  1-05  and 
a  boiling-point  of  179°  C.  It  is  used  in  perfumery  and  for 
flavouring  purposes.  (See  Glucosides.) 

BENZAMIDE— See  Amides. 

BENZAMINE  HYDROCHLORIDE— An  organic  compound 
used  in  medicine. 

BENZAMINE  LACTATE  (C15H21NO2.C3H6O3)  —  A  white 
crystalline  organic  compound,  soluble  in  water  and  alcohol, 
used  in  medicine  and  for  the  production  of  eucaine. 

BENZENE  (C6H6)— A  liquid  hydrocarbon  of  sp.  gr.,  0-8784, 
and  boiling-point,  797°  C.,  obtained  from  the  products  of 
the  distillation  of  coal.  It  is  colourless,  inflammable,  of 
characteristic  odour,  soluble  in  alcohol  and  ether,  and 
can  be  prepared  in  a  crystalline  state  by  freezing  the  pure 
liquid.  It  is  an  excellent  solvent  of  resin  and  fats,  and  in 
a  crude  form  is  extensively  used  as  a  fuel  for  motors,  also 
as  a  primary  material  in  the  manufacture  of  aniline  dyes 
and  many  other  carbon  compounds. 

It  is  the  initial  member  of  a  series  of  hydrocarbons,  and 
can  be  obtained  pure  by  distillation  of  a  mixture  of  benzoic 
acid  and  lime.  (See  Hydrocarbons.) 

It  is  the  chief  constituent  of  the  commercial  product 
known  as  "  solvent  naphtha."  '(See  Coal.) 

By  oxidation  with  potassium  permanganate  it  is  slowly 
converted  into  formic  and  oxalic  acids. 

BENZIDINE  (C12H12N2  or  C6H4NH2NH2C6H4)— A  derivative 
of  diphenyl,  being  a  greyish-yellow,  crystalline,  basic  body 
which  melts  at  127°  C.  and  boils  at  400°  C.  It  is  soluble 
in  alcohol,  ether,  and  hot  water,  and  is  of  importance  in 
the  colour  industry,  because  the  so-called  "  substantive  " 
colours,  which  dye  unmordanted  cotton  directly,  can  be 
obtained  from  it.  Congo  red  and  chrysamine  belong  to 
this  group  of  colours. 

Benzidine  is  prepared  by  reducing  nitrobenzene  with 
zinc  dust  in  alkaline  solution,  or  by  the  electrolysis  of  that 
substance,  followed  by  distillation. 

BENZIL  (C14H10O2) — A  yellow  crystalline  compound  obtained 
by  oxidizing  benzoin  with  nitric  acid,  which  melts  at  95°  C., 
and  is  soluble  in  alcohol  and  ether. 

BENZINE  is  not  synonymous  with  benzene,  but  is  a  light 
petroleum  oil.  Persian  benzine  contains  only  2-32  per 


BENZINE— BENZYL  CHLORIDE  57 

BENZINE  (Continued}— 

cent,  benzene,  and  this  is  associated  with  toluene,  xylene, 
and  many  other  hydrocarbons. 

BENZOIC  ACID  (C7H6O2  or  C6H5,CO2H)  can  be  obtained  in 
colourless,  needle-shaped  crystals  from  gum  benzoin  by 
sublimation  and  occurs  naturally  in  the  resins  named 
"  dragon's  blood  "  and  balsam  of  tolu,  although  it  is  chiefly 
made  from  toluene  by  an  oxidation  process.  It  is  but  little 
soluble  in  cold  water,  dissolves  readily  in  hot  water,  and  is 
soluble  in  alcohol  and  ether  ;  sublimes  readily ;  melts  at 
120°  C.,  and  boils  at  250°  C.  When  heated  in  admixture 
with  lime  it  is  decomposed,  benzene  and  carbon  dioxide 
being  produced.  It  is  used  in  the  manufacture  of  aniline 
blue,  possesses  antiseptic  properties,  and  finds  use  also  in 
perfumery  and  in  medicine. 

BENZOIC  ANHYDRIDE  (C14H10O3  or  (C6H5,CO)2O)— A  crys- 
talline substance  soluble  in  water  and  analogous  to  acetic 
anhydride ;  melting-point  39°  C. 

BENZOIN  (C14H12O2) — A  glistening,  yellowish,  crystalline  body 
which  melts  at  134°  C.,  and  is  polymeric  with  benzaldehyde. 

BENZOIN  GUM  is  a  resin  which  flows  from  the  bark  of  Styvax 
benzoin,  a  tree  that  grows  in  Sumatra,  Borneo,  Java,  and  Siam. 
It  has  a  pleasant  smell,  melts  when  heated,  is  soluble 
in  alcohol,  and  is  a  mixture  of  several  resins  containing 
benzoic  and  cinnamic  acids,  which  can  be  dissolved  out  of 
it  by  boiling  water,  or  extracted  to  some  extent  by  heating 
(sublimation).  It  is  used  as  a  source  of  the  acids  it  contains 
and  in  varnish-making. 

BENZOL  (Solvent  naphtha) — Commercial  benzene,  contain- 
ing benzene  (C6H6),  toluene  (C?H8  or  C6H5(CH)3),  xylene 
(C6H4.2CH3),  etc. 

It  is  a  nearly  colourless  liquid  of  sp.  gr.  0-878,  boiling  at 
about  80°  C.,  soluble  in  alcohol  and  ether,  and  is  obtained 
from  the  distillation  of  coal-tar  and  by  scrubbing  coke-oven 
gas.  (See  Coal.) 

BENZOYL  PEROXIDE  (C14H10O4)— A  crystalline,  explosive, 
oxidizing  and  drying  agent,  which  melts  at  106°  C. 

BENZO-NAPHTHOL,  or  NAPHTHOL  BENZOATE  (C6H5CO2 
C10H7) — A  white  substance  used  medicinally  as  an  intestinal 
antiseptic,  when  it  splits  up  into  naphthol  and  benzoic 
acid.  It  melts  at  107°  C.,  and  is  soluble  in  hot  alcohol. 

BENZYL  CHLORIDE  (C6H5CH2C1)— A  colourless  aromatic 
liquid,  prepared  by  chlorinating  boiling  toluene;  sp.  gr.. 
1-1027,  and  boiling-point  179°  C. ;  used  for  the  preparation 
of  oil  of  bitter  almonds  and  certain  dyes. 


58  BERBERINE—BILE 

BERBERINE  (C20H17NO4,H2O)— A  crystalline  alkaloidal  body 
without  marked  physiological  properties  found  present  in 
the  roots  of  Hydvastis  canadensis.  It  is  soluble  in  water  and 
alcohol ;  melting-point  145°  C. 

BEEGAMOT — The  yellowish-green  essential  oil  of  the  Citrus 
bergamia,  which  grows  in  South  Europe.  It  contains  ter- 
penes,  has  a  sp.  gr.  of  0-88 1  to  0*885  '•>  refractive  index, 
i  -465  to  i  -470 ;  optical  rotation  +9°  to  +15°;  and  is  used 
in  perfumery. 

BERYL — A  mineral  consisting  of  a  double  silicate  of  aluminium 
and  glucinum. 

BERYLLIUM— See  Glucinum. 

BERZELIANITE — A  rare  mineral,  consisting  of  copper  selenide 
associated  with  silver,  thallium,  and  iron. 

BESSEMER  PROCESS— See  Iron. 

BETAI'NE  (C6HUNO2,H2O)— A  colourless  alkaloidal  body  of 
crystalline  nature  contained  in  molasses  of  beet  sugar. 

BETA-NAPHTHOL  (C10H8O  or  C10H7OH)  is  contained  in  and 
obtained  from  coal-tar  in  the  form  of  white,  glistening, 
crystalline  plates  with  a  phenolic  odour.  It  melts  at  122°  C., 
and  boils  282°  C.,  can  be  purified  by  sublimation,  and  is 
soluble  in  alcohol  and  ether.  It  constitutes  the  starting-point 
from  which  a  number  of  dyes  are  obtained,  and  is  used 
medicinally  as  an  intestinal  antiseptic  in  diarrhoea  of  children. 

BETEL — A  mixture  of  the  leaves  of  the  betel  pepper,  Piper 
betel  L.,  with  the  fruit  of  the  Areca  catechu,  used  in  tropical 
Asia  as  a  masticatory,  and  in  medicine. 

BICHROMATES— See  Chromium. 

BILE  is  the  secretion  of  the  liver  as  discharged  into  the 
duodenum,  and  plays  an  important  part  in  the  process 
of  food  digestion.  It  is  a  viscid  liquid  of  yellowish-green 
colour,  which  becomes  more  yellow  on  dilution,  of  sp.  gr. 
about  1*02,  and  owes  its  viscidity  to  the  presence  of  a 
quantity  of  mucus  derived  from  the  gall-bladder.  It 
consists  of  more  than  90  per  cent,  water,  but  the  biliary 
matters  proper,  contain  taurocholate  and  glycocholate  of 
sodium,  several  colouring  matters  (the  chief  of  which  are 
bilirubin  and  bilifuscin  (C16H20N2O4),  also  a  small  quantity 
of  cholesterin,  lecithin,  and  choline. 

Glycocholic  Acid  (C26H43NO6),  as  obtained  from  the  bile, 
when  pure,  crystallizes  in  long  silky  needles,  which  are 
freely  soluble  in  hot  water  ;  melting-point  133°  C. 

Taurocholic  Acid  (C26H45NSO7)  contains  sulphur  as  one 
of  its  constituents.  Both  of  these  acids  can  be  made  to. 


BILE— BISMUTH  59 

BILE  (Continued) — 

yield  Cholic  Acid  (C20H40O5),  and  that  substance  in  turn 
is  said  to  yield  a  fatty  acid  of  the  stearic  series  when 
oxidized.  Bilirubin  (C16H18N2O3)  has  a  brilliant  red 
colour,  but  quickly  changes  into  the  green  biliverdin 
(C16H18N2O4),  when  bile  is  exposed  to  the  air.  It  is  the 
bile  that  gives  colouring  matter  to  the  faeces. 
BIOPLASM,  sometimes  called  protoplasm,  is  the  most 
elementary  living  matter  in  the  animal  and  vegetable 
kingdoms,  being  the  germinal  substance  from  which  all 
living  creatures  build  up  their  structures  by  assimilation. 
It  is  of  an  albuminous  character. 

BISMUTH  (Bi) — Atomic  weight,  208  ;  sp.  gr.,  9-823  :  melting- 
point,  271°  C.  Bismuth  occurs  in  nature  mainly  in  the 
metallic  state,  also  combined  with  oxygen  as  bismuth  ochre 
(Bi2O3),  with  sulphur  as  bismuth  glance  (Bi2S3).  and  with 
tellurium  as  tetradymite  (a  natural  telluride  found  in 
Arizona,  California,  etc.).  It  is  also  found  as  bismuthinite 
(a  sulphide  of  the  metal  occurring  in  association  with  gold 
in  Rowan  Co.,  N.C.),  as  bismuth-gold  (Au2Bi)  at  Maldon, 
Victoria,  and  in  association  with  antimony  in  kobellitet 
hauchecornite  and  chiviatite. 

It  is  a  lustrous,  white,  brittle  metal  of  a  reddish  tinge, 
forming  beautiful  crystals,  and  forms  alloys  with  other 
metals,  of  which  one  of  the  best  known  is  Wood's  fusible 
metal,  which  is  made  of  4  parts  bismuth,  2  of  lead,  i  of 
tin,  and  i  of  cadmium,  and  melts  at  6o'5°  C. 

It  is  made  from  its  metallic  ores  by  a  process  of  roasting 
to  remove  sulphur,  and  is  subsequently  refined  when  re- 
quired in  the  pure  state,  by  conversion  into  nitrate  and 
reduction  by  heating  with  charcoal. 

Among  its  compounds  are  two  chlorides  (BiCl2  and 
BiCl3),  two  or  more  oxides,  of  which  the  trioxide  (Bi2O3) 
alone  is  of  any  commercial  importance ;  it  is  a  yellowish 
insoluble  powder  of  sp.  gr.  8'2,  prepared  by  heating  the 
carbonate  or  nitrate,  and  is  used  in  the  manufacture  of 
crystal  glass  to  replace  lead  oxide.  When  acted  upon  by 
acids  the  oxides  give  salts,  including  bismuth  nitrate 
(Bi(NO3)3)  and  bismuth  sulphate  (Bi2(SO4)3). 

Bismuth  subnitrate,  (BiO)NO3,H2O  (a  heavy  white 
powder,  used  in  medicine  and  in  preparing  enamels,  fluxes, 
and  cosmetics),  is  prepared  by  adding  bismuth  nitrate  to 
water,  which  decomposes  it,  as  represented  thus  : 

Bi(N03)3  +  2H20  =  (BiO)N03,H20  +  2HNO8. 
Bismuth  sulphide  (Bi2S3)  is  a  black  insoluble  body. 


60  BISMUTH— BLEA  CHING 

BISMUTH  (Continued} — 

Bismuth  chromate  (Bi2O3.2CrO3)  is  a  yellow  amorphous 
substance  used  as  a  pigment. 

Many  of  the  bismuth  salts  are  used  in  medicine  and  are 
for  the  most  part  insoluble  in  water;  among  others  used  in 
medicine  are  the  betanaphtholate  (orphol)  (Bi(C10H6OH)3); 
salicylate(Bi(C7H6O3)34H2O);  a  subsalicylate(Bi(C7H5O3)3 
Bi2OJ,  and  the  tribromophenylate  (xeroform)  (Bi2O3 
(C6H2Br3OH)). 

BISMUTITE — A  natural  basic  bismuth  carbonate  which  yields 
about  90  per  cent,  of  the  oxide  Bi2O3  ;  found  in  auriferous 
quartz  in  the  Transvaal. 

BITTERN — The  mother-liquor  of  sea-water  left  after  crystal- 
lization of  its  salts,  formerly  used  as  a  source  of  bromine. 

BITTERS  are  bodies  extracted  from  vegetable  productions, 
and  include :  'quassia,  from  quassia  wood ;  wormwood, 
from  the  herb  of  that  name ;  aloe,  from  the  juice  of  the 
plant ;  angostura,  from  bark ;  orange,  from  the  peel  ; 
acorus,  from  the  root  of  the  common  sweet  flag ;  cascarilla, 
from  bark ;  camomile,  from  the  flowers ;  colocynth,  from 
the  fruit  (Citrullus  colocynthis). 

BITUMENS— Soft  deposits  constituted  of  hydrocarbons  of 
complicated  composition,  often  found  in  association  with 
petroleum — as,  for  example,  at  Trinidad.  They  are  soluble 
in  carbon  disulphide  and  Russian  turpentine,  and  are 
largely  used  for  paving  purposes,  making  varnishes,  and  for 
lining  and  cementing  water-tanks,  etc.  (See  Asphalt.) 

BLACK  ASH — The  crude  sodium  carbonate  as  made  in  the 
Leblanc  process.  (See  Alkali  Trade,  and  Sodium  carbonate. 

BLACK-BAND— See  Iron. 
BLACK-DAMP— See  Carbon. 

BLACKING  is  commonly  made  from  bone-black,  sugar,  and 
oil,  with  the  addition  sometimes  of  a  little  vinegar  or  strong 
sulphuric  acid  :  there  are,  however,  many  recipes. 

BLACKSTRAP— See  Molasses. 
BLANC  FIXE — See  Barium  sulphate. 
BLACK-LEAD— See  Carbon. 

BLEACHING — An  operation  largely  employed  in  the  arts,  a 
number  of  chemical  agents  being  used  therefor. 

Bleaching-powder  (see  Chlorine)  is  used  on  an  immense 
scale,  the  materials  to  be  bleached,  such  as  calicoes  and 


BLEA  CHING— BLOOD  61 

BLEACHING  (Continued)— 

other  fabrics,  rags  for  paper-making,  etc.,  being  first 
steeped  in  a  dilute  solution  (2  to  2  J  per  cent,  strength)  of 
the  bleaching-powder  and  then  in  dilute  acid.  In  the  case 
of  calico,  the  fabric  is  first  of  all  well  washed,  and  boiled 
successively  with  lime-water,  much  dilute  sulphuric  acid, 
and  weak  caustic  soda,  to  remove  the  weavers'  dressing, 
greasy  and  resinous  matters,  etc. 

Hypochlorous  acid  (HC1O),  which  may  be  said  to  act  in 
the  same  way  (being  practically  the  active  principle  of  bleach- 
ing-powder),  also  serves  the  same  purposes,  readily  giving 
up  oxygen.  It  is,  however,  a  somewhat  explosive  substance 
and  undergoes  rapid  decomposition  on  exposure  to  the  air. 

At  one  time,  particularly  in  France,  a  solution  of  sodium 
hypochlorite  was  extensively  used  for  bleaching,  being 
prepared  under  the  name  of  Eau  de  Javelle. 

Sulphur  dioxide  (SO2)  also  exhibits  powerful  bleaching 
effects,  and  is  largely  used  for  bleaching  straw,  woollen, 
and  silk  goods,  isinglass,  sponge,  and  other  articles  which 
would  be  injured  by  the  use  of  chlorine  compounds.  To 
effect  this,  they  have  to  be  moistened  and  exposed  to  its 
fumes  as  generated  by  burning  sulphur  or,  alternatively, 
treated  with  a  dilute  solution  of  the  gas  dissolved  in  water 
(sulphurous  acid). 

Peroxide  of  hydrogen  or  hydrogen  dioxide  (H2O2)  is  a 
very  valuable  bleaching  agent,  readily  parting  with  its 
second  constituent  atom  of  oxygen,  and  has  the  great  advan- 
tage of  being  perfectly  innocuous  to  operators  and  goods. 
It  is  largely  used  in  respect  of  delicate  fabrics,  straw  goods, 
human  hair,  ivory,  etc. 

The  old  practice  of  bleaching  linen  and  other  materials, 
but  particularly  hempen  and  flaxen  goods,  by  exposing 
them  to  the  air  is  referred  to  in  the  article  on  Light,  and 
is  probably  due  to  the  production  of  hydrogen  dioxide  by 
sunlight  action  on  moisture  and  oxygen. 

BLEACHING  POWDER— See  Chlorine  and  Alkali  Trade  Chart. 
BLENDE— See  Zinc. 

BLOOD  is  built  up  from  the  digested  food  and  serves  to  supply 
all  parts  of  the  organism  with  fresh  nutrient  materials  to 
replace  those  worn  out  by  the  processes  of  life,  and  it  also 
dissolves  and  carries  away  the  excretory  products.  It  is 
by  the  medium  of  the  blood  that  the  great  process  ot 
oxidation  through  respiration  is  effected.  It  is  alkaline  in 
reaction,  and  has  a  sp.  gr.  ranging  from  1*055  to  1*062,  its 
temperature  in  the  living  body  being  about  37-8°  C.  (100°  F.). 


62  BLOOD— BONES 

BLOOD  (Continued)— 

Besides  the  other  small  chemical  differences  between 
arterial  and  venous  blood,  there  is  the  greater  divergence 
in  the  matter  of  oxidation  dependent  upon  the  oxygen-carry- 
ing capacity  of  the  red  colouring  matter  (haemato-crystalline 
or  haemoglobin),  which  contains  iron  and  consists  of  a 
combination  of  hematine  (C32H3oFeN4O3)  with  a  certain 
albuminous  substance.  Blood  contains  seralbumin,  fibrin, 
and  globulin  in  solution,  together  with  a  great  number  of 
other  substances  more  or  less  definitely  ascertained  in  addi- 
tion to  its  saline  constituents.  (See  also  Fibrin  and  Serum.) 
The  clotting  of  blood  is  accompanied  by  an  enzyme  found 
therein  named  thrombin. 

BLOOD  ALBUMIN  (Seralbumin)— Prepared  from  the  serum 
of  the  blood  of  animals,  finds  use  in  commerce  in  connec- 
tion with  printing  colours  on  calico  fabrics.  It  is  contained 
in  blood  to  the  extent  of  about  0*08  per  cent,  the  serum 
itself  amounting  to  about  48-16  per  cent. 

BLOOD-STONE — A  variety  of  jasper  (native  silica,  SiO2). 

BLOW-PIPES — Appliances  for  intensifying  the  heat  of  flame 
by  blowing  air  into  admixture  with  the  burning  gas.  As 
to  the  character  of  the  blow-pipe  flame,  see  Burners. 

BLUE  STONE  and  BLUE  VITRIOL— Common  names  for 
copper  sulphate.  (See  Copper.) 

BOILED  OIL  (blown  oil) — See  Linseed  oil. 

BOILING-POINT — The  highest  temperature  at  which  any  liquid 
can  be  converted  into  vapour  at  the  standard  pressure  of 
760  mm.  of  mercury;  or,  the  temperature  at  which  its 
vapour  pressure  is  equal  to  the  atmospheric  pressure. 

BOLE — A  sort  of  clay  coloured  with  iron.  Armenian  bole  is  of 
a  bright  red  colour;  other  kinds  are  yellow  or  yellowish-red. 

BONES — Dry  bones  contain  about  30  per  cent,  of  ossein, 
which,  when  dissolved  in  water,  yields  gelatin,  and  the 
following  table  gives  the  average  composition  : 

Water  and  ossein         ...         ...  30  to  34  per  cent. 

Calcium  phosphate      ...         ...  45  to  52         ,, 

„        carbonate       ...         ...       6  to  14         ,, 

„  fluoride  i  to  2  „ 

Magnesium  phosphate  ...  0-8  to  1-2        „ 

Other  salts         traces 

Bone-earth  (bone-ash)  contains  about  87  to  88  per  cent, 
calcium  phosphate  (Ca3(PO4)2),  9  per  cent,  calcium  carbo- 


BONES— BORON  63 

BONES  (Continued)— 

nate,    3    per    cent,   calcium    fluoride,    and    1-7    per    cent, 
magnesium  phosphate. 

BONE-BLACK — An  impalpable  form  of  carbon  (prepared  by 
burning  bones,  and  subsequently  dissolving  out  the  calcium 
and  other  mineral  salts  by  means  of  acid  applications), 
used  for  decolorizing  solutions,  as  in  sugar  refining.  (See 
Carbon.) 

BONE-MEAL— See  Phosphorus. 
BONE-OIL— See  Dippel's  Oil. 
BORACIC  ACID — See  Boron. 
BORACITE— See  Boron. 
BORAX— See  Boron. 

BORDEAUX  MIXTURE — A  liquid  insecticide  and  fungicide 
made  from  copper  arsenite  ;  used  in  orchards,  vineyards,  etc. 

BORNEOL,  or  SOLID  CAMPHOR  OF  BORNEO  (C10H18O  or 
C10H17OH),  is  found  in  cavities  in  the  trunk  of  old  trees  of 
the  order  Dryobalanops  camphora.  It  consists  of  small,  colour- 
less crystals  (resembling  ordinary  camphor  and  pepper  in 
odour),  which  melt  at  208°  C.  It  is  nearly  allied  to  ordi- 
nary camphor,  from  which  it  can  be  prepared  by  reduction 
with  nascent  hydrogen — C10H16O  +  2H  =  C10H18O.  It  is 
used  in  medicine  and  in  the  celluloid  industry.  (See 
Camphor. ) 

BORNITE — A  mineral  double  sulphate  of  copper  and  iron 
(3Cu2S,Fe2S3). 

BORON  (B)  and  its  compounds — Atomic  weight,  n.  Boron 
occurs  naturally  in  a  number  of  combinations,  one  of  the 
best  known  being  tincal,  a  crude  borate  of  sodium  or  borax 
(Na2B4O7ioH2O),  and  this  in  a  purified  form  is  largely 
used  for  cleansing  and  other  purposes.  Borax  is  found 
naturally  in  Thibet,  California,  and  elsewhere.  In  com- 
bination with  calcium,  boron  is  also  found  in  the  forms  of 
boracite  and  colemanite  or  borate  spar  (Ca2B6Ou),  and  as  ulexite 
(Ca2B6Ou,Na2B4O7,i6H2O),  a  compound  borate  of  cal- 
cium and  sodium  found  in  Nevada  and  California. 

The  composition  of  some  borate  minerals,  as  taken  from 
a  pamphlet  recently  issued  by  the  Imperial  Mineral 
Resources  Bureau,  is  as  follows  : 


64 

BORON  (Continued)— 


BORON 


Colemanite. 

Ulexite. 

Boracite. 

(California.) 

(Chili  and  Peru.) 

(Asia  Minor.) 

Boric  acid 

40-19 

44-38 

45'89 

Lime... 

31-89 

16-14 

30-62 

Magnesia 

1-50 

0-91 

0'53 

Iron  and  alumina    .  .  . 

0'62 

0-48 

0-98 

Soda  

— 

6-50 

— 

Sodium  chloride 

— 

7-46 

— 

Carbon  dioxide 

8-53 

— 

— 

Sulphur  trioxide 

0-26 

3*35 

I-25 

Water   and   organic 

matter 

5-83 

16-25 

17-09 

Insoluble  matter 

II-I8 

471 

3  '64 

Total     

100-00 

100-18 

100-00 

In  the  elemental  state,  boron  is  a  soft  greenish-brown 
powder,  but  it  can  be  obtained  in  almost  colourless  crystals 
having  a  density  of  2-63.  The  melting-point  of  boron  lies 
between  2,200°  and  2,500°  C.  There  are  several  methods 
of  preparing  this  element,  one  of  which  consists  in  heating 
potassium  in  the  vapour  of  boron  trichloride  as  shown  by 
the  equation — 

3K  +  BC13=3KC1  +  B, 

and  another  in  heating  metallic  potassium  or  sodium  in 
admixture  with  boron  trioxide — 

6K  +  2B2O3  =  3K2O2  +  46. 

The  purest  boron  is  said,  however,  to  be  obtained  by  the 
reduction  of  boron  trichloride  with  hydrogen  in  the  high- 
tension  electric  arc.  When  heated  strongly  in  the  air 
boron  burns  and  combines  with  both  oxygen  and  nitrogen, 
forming  the  trioxide  and  nitride  (B2O3  and  BN). 

Boron  is  sometimes  added  to  metallic  castings,  especially 
those  of  aluminium  and  nickel,  to  strengthen  them. 

Boric  or  Boracic  Acid  (B(HO)3)  is  found  naturally  in  the 
water  and  steam  jets  of  volcanic  eruptions  in  Tuscany  and 
elsewhere,  and  is  obtained  commercially  from  such  sources. 
It  is  soluble  in  water  and  in  a  purified  condition  it  finds 


BORON  AND  ITS  COMPOUNDS  65 

BOEON  (Continued)— 

many  medicinal  applications,  while  it  is  also  largely  used 
in  glass-making  and  metallurgy  as  a  flux,  and  as  a  pre- 
servative agent  of  perishable  articles. 

Borax  can  be  made  from  boric  acid  by  adding  anhydrous 
sodium  carbonate  to  a  boiling  solution  of  the  acid,  when 
the  following  change  takes  place — 

4B(HO)3  +  Na2CO3  =  Na2B4O7  +  6H2O  +  CO2. 

That  is  to  say,  borax  is  produced  in  solution,  and  carbon 
dioxide  is  evolved,  and  from  the  liquid  the  borax  is  crystal- 
lized out  in  combination  with  water  (Na2B4O7ioH2O).  It 
occurs  naturally  in  California  and  elsewhere,  and  only 
requires  purification  by  recrystallization.  It  is,  however, 
chiefly  produced  from  the  Bolivian  deposits  of  calcium 
borate  by  boiling  the  powdered  mineral  in  water  and 
addition  of  soda-ash — 

Ca2B6On  +  2Na2CO3  =  2CaCO3  +  Na2B4O7  +  Na2B2O4. 

That  is  to  say,  calcium  carbonate  is  precipitated  and  the 
borax  is  crystallized  out  of  the  solution,  leaving  the  sodium 
metaborate  (Na2B2O4)  in  solution,  and  this  is  afterwards 
converted  into  a  further  quantity  of  borax  by  treatment 
with  carbon  dioxide — 

2Na2B2O4  +  CO2  =  Na2C03  +  Na2B4Or 

Borax  is  used  as  a  food  preservative  ;  also  in  the  textile 
and  tanning  industries,  as  a  sanitary  reagent,  and  in  ceramics, 
being  prepared  in  various  forms,  such  as  powder,  crystals, 
fused  state,  etc. 

When  crystalline  borax  is  heated,  it  loses  its  associ- 
ated water  and  passes  into  a  fused  glassy  mass,  which  pos- 
sesses the  power  of  dissolving  many  metallic  compounds, 
so  that  it  is  used  in  the  laboratory  for  analytical  purposes, 
the  colour  which  is  communicated  to  the  bead  of  fused 
material  being  indicative  of  the  substance  under  examina- 
tion. For  example,  using  a  looped  platinum  wire,  it  can  be 
made  to  take  up  a  small  quantity  of  borax,  which  can  then 
be  fused  so  as  to  make  a  clear  bead  in  the  loop  by  heating 
and  dipping  afresh  in  the  borax  whilst  still  hot  until  it  is 
sufficiently  large.  If  such  a  bead  be  touched  with  a  com- 
pound of  cobalt,  it  will,  upon  remelting  and  subsequent 
cooling,  be  found  to  have  an  azure  or  deep  blue  colour, 
according  to  the  quantity  of  cobalt  used. 

Manganese  compounds  communicate  a  violet,  lilac,  or 

5 


66  BORON—  BRANDY 

BORON  (Continued)— 

purple  colour  if  the  bead  be.  heated  in  the  outer  (oxidizing) 
flame  of  a  blow-pipe  ;  but  this  colour  is  lost  if  the  bead  be 
heated  in  the  inner  (reducing)  flame,  owing  to  chemical 
changes  that  occur  under  these  different  circumstances. 

Borax  is  a  valuable  flux,  and  is  used  in  manufacturing 
pottery  glazes  and  enamels,  also  as  a  glaze  for  linen  and 
paper.  It  is  also  employed  in  tanning,  in  the  manufacture 
of  glue,  soap,  and  glass,  and  as  a  food  preservative. 

Boron  trichloride  (BC13)  is  produced  by  heating  boron  in 
a  current  of  dry  chlorine,  and  is  a  mobile,  colourless  liquid, 
boiling  at  a  little,  over  18°  C.  It  is  decomposed  by  water, 
forming  boric  and  hydrochloric  acids. 

There  is  a  corresponding  trifluoride  of  boron. 

Boron  Nitride  is  a  white  amorphous  powder,  which,  when 
boiled  in  caustic  alkaline  solution,  is  decomposed  with  the 
production  of  ammonia  — 


BN  +  3KHO  =  KBO3  -H  NH 


Boron  triethyl  (B(C2H5)3)  is  a  spontaneously  inflam- 
mable liquid,  and  the  analogous  boron  trimethyl  (B(CH3)3) 
is  a  gas  of  very  unpleasant  character. 

BOTTLES  are  generally  made  of  glass,  but  some  are  made 
of  gutta-percha  for  holding  liquids  that  act  upon  glass, 
such  as  hydrofluoric  acid. 

BOYLE'S  LAW  OF  PRESSURE—  See  Gases. 

BRAIN-MATTER  contains  from  80  to  90  per  cent,  water, 
the  tissue  being  a  mass  of  colloid  matter  of  which  the 
envelope  is  of  an  albuminous  character,  whilst  the  con- 
stituent parts  are  of  very  complicated  chemical  consti- 
tution, comprising  a  number  of  phosphorized  substances 
including  lecithin  (which  yields  glycerophosphoric  acid 
(C3H9PO6)  and  a  base  named  neurine  (C5H13NO)  upon 
hydrolysis);  a  so-called  cerebrine  group  of  substances 
which  appear  to  be  of  a  glucoside  nature,  cholesterin 
(C26H44O),  and  a  number  of  extractive  matters. 

BRANDY  —  Real  spirits  of  wine  as  prepared  by  the  distillation 
of  fermented  wines  (generally  coloured  with  burnt  sugar 
or  caramel) 


BRA  NNERITE— BROMINE  67 

BRANNERITE — A  new  uranium  mineral,  obtained  from  gold 
placers  in  Idaho  ;  found  in  the  pegmatites.  It  is  described 
as  a  complex  titanate  of  uranium,  associated  with  smaller 
quantities  of  rare  earths,  including  as  much  as  50  per  cent, 
of  uranium  oxides. 

BRASS— See  Alloys,  Zinc,  and  Copper. 

BRAXJNITE — A  manganese  ore  of  the  composition  3Mn2O3, 
MnSiO3 — that  is,  a  compound  oxide  and  silicate,  occur- 
ring in  Sweden,  the  United  States  of  America,  and  India. 

BRAZIL-NUT  OIL— See  Castanha  Oil. 

BRAZIL  WOOD  DYES  are  red  and  orange,  and  are  extracted 
from  the  wood  of  the  Casalpina  crispa  by  boiling  water.  They 
are  used  for  dyeing  articles  of  silk  and  wool. 

BREWING— See  Beer. 

BRICKS  are  made  from  clay  or  the  mixture  of  clay  and  sand 
called  loam,  as  also  marl  (which  consists  of  clay  and  lime),  by 
moulding  and  baking. 

BRITANNIA  METAL — See  Alloys,  Antimony,  and  Tin. 
BRITISH  GUM— See  Starch. 

BROMINE  (Br)— Atomic  weight,  80;  sp.  gr.,  3-188  at  o°  C. ; 
boiling-point,  58*7°  C.  Bromine  is  found  in  sea-water  in 
combination  with  potassium,  sodium,  and  magnesium,  and 
more  abundantly  in  certain  mineral  waters  and  salt  springs. 
The  Stassfurt  saline  deposits  of  Germany  contain  it  (com- 
bined with  magnesium)  in  larger  amount  in  carnallite,  from 
which  it  is  chiefly  made. 

In  the  manufacture  of  potassium  chloride  from  carnallite, 
there  is  produced  a  mother-liquor  containing  about  J  per 
cent,  of  bromine  as  magnesium  bromide,  and  the  bromine 
is  obtained  from  this  salt  by  heating  it  with  superheated 
steam,  on  admixture  with  manganese  dioxide  and  sulphuric 
acid,  or  by  decomposition  with  chlorine  (which  replaces  it 
in  combination),  the  bromine  being  set  free  in  vaporous 
state  and  condensed  in  cooled  stoneware  coils. 

During  the  recent  war  France  obtained  a  considerable 
quantity  of  bromine  from  deposits  in  the  salt  marshes  or 
lagoons  of  Tunisia. 

Bromine  is  a  heavy,  mobile  liquid  of  a  red-brown  colour 
and  strong,  unpleasant  smell.  It  gives  off  vapour  of  the 
same  colour  when  exposed  to  the  air — that  is  to  say,  it  is 
very  volatile.  At  -  7°  C.  it  solidifies  to  a  crystalline  mass. 
It  is  very  poisonous,  has  a  strong  corrosive  action  on  the 
skin,  and  is  soluble  in  water,  alcohol,  and  ether. 


68  BROMINE-BRUCITE 

BROMINE  (Continued)— 

Bromine  is  used  in  the  dye  industry,  in  organic  synthesis, 
and  the  production  of  bromides. 

The  soluble  salts,  sodium  bromide  (NaBr),  potassium 
bromide  (KBr),  and  ammonium  bromide  are  all  used  in  the 
preparation  of  certain  medicinal  sedative  mixtures. 

Hydrobromic  Acid  or  Hydrogen  Bromide  (HBr),  cor- 
responding to  hydrochloric  acid,  is  produced  when  a  mixture 
of  hydrogen  and  bromine  vapour  is  burned  or  passed  over 
a  spiral  wire  of  platinum  maintained  at  a  bright  red  heat. 
There  are  a  number  of  other  methods  by  which  it  can  be 
produced.  It  is  a  colourless  gas  of  pungent  odour,  which 
fumes  in  the  air  and  is  very  soluble  in  water,  the  aqueous 
solution  resembling  one  of  hydrochloric  acid  in  its  general 
chemical  behaviour. 

Bromic  Acid  (HBrO3)  is  only  known  in  solution,  and  it 
forms  bromates  corresponding  to  the  chlorates  by  corre- 
sponding reactions,  potassium  bromate  having  the  formula 
KBrO3. 

BROMITE — Native  silver  bromide. 

BROMOFORM  (CHBr3)— A  colourless  heavy  liquid  of  sp.  gr. 
2-8887,  soluble  in  alcohol  and  ether;  corresponding  to 
chloroform  and  iodoform  ;  used  in  medicine,  etc. 

BROMYRITE— Natural  silver  bromide  (AgBr)  containing 
57  per  cent,  of  silver,  found  in  New  Mexico  and  Nevada. 

BRONZE— See  Alloys,  Copper,  and  Tin. 
BRONZE  BLUES — Forms  of  Prussian  blue. 

BRONZE  POWDERS— Used  for  japanning  and  other  decorative 
applications,  and  made  of  many  shades,  are  compounded  of 
alloys  of  various  metals — copper,  zinc,  iron,  tin,  vanadium, 
etc. — reduced  to  powder,  with  or  without  admixture  with 
other  compounds,  according  to  the  desired  colour  and 
properties. 

BROOKITE— See  Titanium. 

BRUCINE  (CMH26N2O4,4H2O)— A  white  crystalline,  nitro- 
genous base,  soluble  in  alcohol,  accompanying  strychnine 
in  nux  vomica.  (See  Nux  Vomica.) 

BRUCITE— A  native  form  of  magnesium  hydroxide  (Mg(HO)2) 
found  in  serpentine  rocks  in  Shetland  and  Texas. 


BRUNSWICK  BLACK— BURNERS  69 

BRUNSWICK  BLACK  is  prepared  by  melting  together 
asphalt  and  boiled  linseed  oil  in  the  proportions  of  2  to  i 
and  adding  two  parts  of  turpentine  to  the  mixture  upon 
cooling. 

BRUNSWICK  GREEN— See  Copper. 

BRUSHITE— A  natural  hydrated  calcium  phosphate  (CaHPO4, 
2H2O)  found  in  the  guano  of  Aves  Island  and  Sombrero. 

BUCHNER  FUNNEL— See  Filters. 

BULBS — See  Potash  Bulbs  ;  also  Organic  Analyses. 

BUNSEN  BURNER— See  Burners. 

BURETTE — A  graduated  glass  tube,  open  at  the  top  and 
drawn  out  below,  fitted  either  with  a  glass  stopcock,  or 
rubber  tubing  and  a  pinch-cock,  for  delivering  measured 
quantities  of  liquids.  (See  Volumetric  Analyses.) 

BURGUNDY  PITCH,  of  genuine  character,  is  made  by  melt- 
ing frankincense  (Abides  resina)  in  water  and  straining  it 
through  cloth,  but  common  rosin  coloured  with  palm  oil  is 
said  to  be  often  substituted  for  it.  It  is  a  yellowish-brown, 
brittle,  resinous  substance,  of  aromatic  odour,  soluble  in 
hot  alcohol,  and  is  used  in  medicine. 

BURNERS — Gas-burners  used  in  laboratories  are  of  various 
types,  according  to  the  application  that  is  to  be  made  of 
them,  apart  from  those  used  for  illumination. 

Fish-Tail  Burner — This  resembles  the  old-fashioned  sort 
used  for  lighting  rooms,  the  flame  of  which  is  like  a  fish- 
tail or  bat's  wing  in  general  form.  It  is  chiefly  used  in 
connection  with  the  bending  of  glass  tubes  (see  Glass 
Tubes),  and  may  be  attached  directly  to  the  gas-supply 
pipe  running  along  the  working  bench  of  the  laboratory, 
or  fixed  on  an  upright  stand  and  connected  therewith  by 
means  of  a  rubber  tube.  The  luminosity  of  the  flame  is 
due  to  the  imperfect  combustion  of  the  gas,  and  consequent 
production  of  minute  particles  of  the  carbon  constituent  in 
an  incandescent  form. 

Bunsen  Burner — This  consists  of  an  iron  or  brass  tube 
fixed  to  a  stand,  and  is  fitted  with  a  mechanical  arrange- 
ment below,  whereby  air  can  be  admitted  in  regulated 
amount  into  admixture  with  the  gas  before  burning.  The 
gas  issues  from  a  small  jet  at  the  base  of  the  tube,  and  the 
air  is  admitted  through  several  small  holes  also  situate 
near  its  base,  the  amount  of  air  being  regulated  by  a 
movable  disc  of  metal  capable  of  closing  these  openings 
more  or  less  as  desired.  In  practice  there  is  used  about 


70  BURNERS— BUTTER 

BURNERS  (Continued)— 

i  part  gas  to  2^  parts  of  air.  By  this  admixture  the  heat 
is  intensified,  perfect  combustion  of  the  carbon  of  the  gas, 
as  also  of  the  hydrogen,  being  secured,  thus  producing  a 
practically  smokeless  blue  flame.  Such  burners  are  often 
provided  with  a  movable  ring  which  fits  on  to  the  top  of 
the  burner  tube,  so  that  the  flame  may,  when  desired,  be 
broken  up  and  made  to  assume  a  rose  or  ring  in  the  form  of 
a  number  of  small  blue  flames,  instead  of  the  one  long 
vertical  column  of  flame.  Both  of  these  forms  are  employed 
for  heating  liquids  contained  in  flasks  or  beakers,  or  for 
heating  solid  substances  contained  in  crucibles,  dishes,  etc.; 
also  for  applying  heat  to  sand-baths,  water-baths,  and 
water-ovens. 

The  flame  of  a  Bunsen  burner  (like  all  ordinary  flames) 
consists  of  two  cones — the  inner  one,  in  which  heated  but 
imperfectly  burned  gases  exist ;  and  the  outer  one,  where 
oxygen  is  in  excess  on  the  outside  edge.  Upon  holding  a 
bright  copper  wire  across  the  flame  so  as  to  bisect  (cut 
across)  the  inner  one,  the  wire  will  become  coated  with 
black  copper  oxide  at  the  outer  edges,  while  that  part  in 
the  centre  will  remain  bright.  If  now  the  blackened  part 
be  placed  in  the  inner  cone,  the  oxide  will  be  reduced  again 
to  the  metallic  state,  parting  with  its  oyxgen  constituent  to 
the  gases  in  course  of  combustion.  The  outer  area  is 
consequently  called  the  oxidizing  flame,  and  the  inner  cone 
the  reducing  flame. 

When  coal  gas  is  burned  in  a  current  of  air,  water  and 
carbon  dioxide  are  among  the  products  of  its  combustion. 

Blow-Pipe  Burners — See  Blow-Pipes. 

BURNT  ALUM — A  white  porous  salt  of  anhydrous  alum  made 
by  heating  ordinary  alum  to  dull  redness. 

BURNT  LIME— See  Calcium. 
BUTANE— See  Hydrocarbons. 

BUTTER — The  fat  of  milk  produced  by  churning,  and  consisting 
of  about  i  real  fatty  matter  and  i  butter-milk,  which  can 
be  separated  by  melting ;  the  fatty  matter  being  composed 
of  palmitin,  myristin,  stearin,  olein,  and  small  quantities  of 
other  glycerides.  It  is  also  said  to  contain  a  small  propor- 
tion of  a  vitamine.  A  recent  investigation  has  shown  that 
there  is  no  material  loss  of  the  "  fat  soluble  A,"  or  growth 
vitamine,  contained  in  butter  during  twelve  months'  storage 
at  a  temperature  of  —8°  to  —  15°  C.  (See  Vitamines.) 


BUTTER— CACAO  71 

BUTTER  (Continued)— 

It  varies  in   composition   within  certain  limits,  but  on 
average  may  be  expressed  as  follows  : 

Per  Cent. 

Fat         86-85 

Curd       0-59 

Salt        102 

Water IJ*54 

lOO'OO 

One  published  analysis  of  dry  butter  is  as  follows  : 

Per  Cent. 
Palmitin,  myristin,  and  other  hard  fats  53 -98 

Olein  37*82 

Butyrin  and  other  constituents 8-20 


100-00 

When  split  up  (hydrolyzed)  butter  yields,  according  to  one 
authority,  as  follows : 

Palmitic  acid,  18-23  per  cent;  myristic  acid,  11-08  per 
cent. ;  lauric  acid,  16-40  per  cent.  ;  stearic  acid,  0-49  per 
cent.;  oleic  acid,  36-10  per  cent.;  caproic,  caprylic,  and 
capric  acids,  3-23  per  cent. ;  butyric  acid,  6*13  per  cent.  ; 
glycerine,  12-50  per  cent. 

Butter  has  a  sp.  gr.  of  0-926  to  0-940 ;  a  saponification 
value  of  about  227 ;  and  an  iodine  value  of  from  26  to  38. 

BUTYL  ALCOHOL— See  Alcohols. 
BUTYLAMINE — See  Amines. 

BUTYRIC  ACID  (C4H8O2  or  CH3(CH2)2CO2H)  is  produced  by 
the  oxidation  of  the  corresponding  butyl  alcohol  and  in  the 
butyric  fermentation  of  sugar  or  starch  being  secondarily 
produced  from  lactic  acid ;  it  also  occurs  in  glyceric  com- 
bination in  butter,  and  communicates  the  so-called  rancid 
odour  to  that  substance  when  stale.  It  is  found  present  in 
the  free  state  in  perspiration  and  in  the  secretions  of  certain 
insects.  It  is  a  colourless  liquid  of  rancid  odour  when 
volatilized,  boils  at  162-4°  C.,  and  nas  a  SP-  gr-  °f  °'95&  to 
0-960.  It  is  used  in  medicine  and  in  varnish-making,  etc. 

CACAO  and  CACAO  BUTTER— The  seeds  of  Theobroma  cacao 
and  other  members  of  the  genus  Stevculiacea  of  Africa, 
South  America,  West  Indies,  and  some  tropical  parts  of 
Asia,  yield  the  nutritive  substances  cocoa  and  chocolate. 
The  beans  contain  much  fatty  matter,  and  about  i  per  cent, 
of  theobromine  (C7H8N4O2),  together  with  about  0-4  per 


!?2  CACAO— CADMIUM 

CACAO  and  CACAO  BUTTER  (Continued)— 

cent,  of  caffeine.  The  aroma  of  cacao  is  due  to  the 
presence  of  about  0*006  per  cent,  of  linalool.  The  fat 
ranges  from  50  to  56  per  cent.  ;  has  the  consistence  of 
suet,  and  consists  of  a  number  of  fats,  including  about 
40  per  cent,  stearine,  about  31  per  cent,  oleic  acid,  and 
some  proportion  of  theobromic  acid  (C64H128O2).  It  is  of 
sp.  gr.  0*858  to  0-865,  melts  at  from  32°  to  34°  C.,  has  an 
iodine  value  of  from  34  to  38,  and  a  saponification  value  of 
192  to  198.  Cacao  butter  is  used  in  pharmacy  and  in 
chocolate-making,  and  is  distinct  from  cocoa-nut  oil,  which 
is  yielded  by  the  cocoa  palm  (Cocus  nucifera).  The  shell  is 
used  in  preparing  cattle  food.  Chocolate  is  a  preparation 
of  roasted  cacao  beans  without  the  abstraction  of  the 
butter,  and  always  contains  sugar  and  added  cacao  butter  ; 
whereas  cacao  is  the  powder  made  from  the  roasted  beans 
by  pressing  out  part  of  the  butter. 

CACODYL — A  methyl  arsenide  (As2(CH3)4)  prepared  by 
heating  a  mixture  of  arsenious  oxide  and  potassium 
acetate.  It  is  a  colourless  liquid,  insoluble  in  water, 
of  most  offensive  garlic-like  odour,  boils  at  170°  C.,  is 
extremely  poisonous,  and  readily  inflammable  in  the  air. 
It  combines  with  chlorine,  and  acts  as  an  organo-metallic 
radical,  forming,  for  example,  cacodyllic  acid,  which  may 
be  represented  as  As(CH3)2HO2.  Cacodyllic  acid  is  a 
colourless,  poisonous,  crystalline  body,  soluble  in  water  and 
alcohol. 

CADAVERINE— See  Ptomaines. 

CADE  OIL— Obtained  by  the  dry  distillation  of  the  wood  of  the 
Juniper  us  oxycedrus.  A  thick,  clear  liquid  of  burning,  bitter 
taste,  with  a  sp.  gr.  of  from  0*98  to  1*06 ;  soluble  in  alcohol 
and  ether  ;  used  in  perfumery,  medicine,  and  for  making 
animal  soap,  etc.  Its  chief  constituent  is  cadinene. 

CADINENE  (ClpH24)— One  of  the  sesquiterpenes  (lyevoro- 
tatory)  occurring  in  the  oils  of  cade,  betel,  camphor,  juniper, 
and  olibanum.  It  is  a  viscous  liquid  of  sp.  gr.  about  0-92, 
and  boiling-point  274°  C. 

CADMIUM  (Cd) — Atomic  weight,  112  ;  sp.  gr.,  8*642  ;  melting- 
point,  320*9°  C.  Found  naturally  in  the  form  of  sulphide 
(CdS)  in  a  rare  mineral  named  Greenockite,  and  in  a  number 
of  zinc  ores,  both  as  sulphide  and  carbonate.  It  is  pro- 
duced in  the  process  of  extracting  zinc  from  its  ores,  being 
found  in  the  first  fractions  coming  over  when  distilling 
them,  partly  in  the  metallic  condition  and  partly  as  oxide, 


CADMIUM -CAJUPUT,  OIL  OF  73 

CADMIUM  (Continued) — 

the  proportion  being  about  i  part  cadmium  to  200  parts 
zinc.  It  can  also  be  recovered  from  the  bag-house  con- 
densation products  from  lead  and  copper  furnaces  by  an 
electrolytic  process. 

An  interesting  property  of  this  metal  is  its  power  of  lower- 
ing the  melting-point  of  certain  alloys  when  incorporated  in 
small  proportion,  thus  making  it  useful  in  the  manufacture 
of  fusible  plugs  in  sprinkler  systems  for  fire  prevention. 

The  metal  is  of  a  bluish-white  colour,  and  its  com- 
pounds include  the  oxide  (CdO),  the  chloride  (CdCl2),  the 
bromide  (CdBr2),  and  the  sulphide  (CdS). 

The  oxide  is  formed  when  the  metal  is  burnt  in  the  air ; 
the  chloride  is  a  soluble  salt  prepared  by  the  action  of 
hydrochloric  acid  upon  the  metal  or  its  oxide  ;  the  bromide 
is  a  yellow  crystalline  body  soluble  in  water  and  used  in 
photography ;  and  the  sulphide,  which  is  yellow  in  colour 
and  insoluble  in  water,  is  used  as  a  pigment  in  oil  and 
water-colour  painting.  Cadmium  nitrate  (Cd(NO3)2.4H2O) 
is  a  white  soluble  salt  used  for  colouring  glass  and 
porcelain. 

CESIUM  (Cs) — Atomic  weight,  132*8  ;  melting-point,  26-5°  to 
28-45°  C.  A  rare  element  belonging  to  the  group  of  alkali 
metals,  found  in  association  with  potassium  and  sodium  in 
some  minerals,  including  porphyrites,  lepidolites,  and  carnal- 
lite,  also  in  certain  mineral  waters  ;  but  the  most  prolific 
source  is  pollux,  or  pollucite,  in  which  it  is  contained  in  the 
form  of  a  compound  silicate  of  aluminium  and  caesium, 
yielding  from  31  to  37  per  cent,  of  the  oxide  Cs2O. 

It  is  a  silver- white,  soft,  ductile  metal,  of  sp.  gr.  I'Sy, 
and  its  compounds  are  very  like  those  of  potassium. 

CAFFEINE  (THEINE)  (C8H10N4O2,H2O)  is  the  alkaloidal 
principle  of  coffee  (which  contains  varying  proportions  up 
to  about  i  per  cent),  kola  nuts,  and  tea  (which  contains 
from  2  to  4  per  cent.).  It  melts  at  236'8°  C.,  and  crystallizes 
from  water -in  white  silky  needles,  having  a  slightly  bitter 
taste.  It  is  soluble  in  chloroform,  not  very  soluble  in 
cold  water,  but  much  more  so  in  boiling  water.  It  can  be 
prepared  from  xanthine.  (See  Coffee.) 

CAJUPUT,  OIL  OF — An  essential  oil  used  in  medicine  which 
is  obtained  in  India  by  distillation  with  water  of  the  leaves 
of  the  Melaleuca  leucodendron  L.  It  is  of  light  green  colour, 
soluble  in  alcohol  and  ether,  containing  cineol  and  terpinol. 
Sp.  gr.,  0-92  ;  optical  rotation,  —  10°  to  -  4°  ;  refractive 
index,  1-460  to  i'466.  (See  Terpenes.) 


74  CALABAR  BEAN— CALCIUM 

CALABAR  BEAN — The  seed  or  bean  of  Physostigma  venosum, 
said  to  contain  an  alkaloid  named  eserine,  a  solution  of 
which  has  an  action  on  the  pupil  of  the  eye  the  opposite  to 
that  which  belladonna  exercises — that  is,  contraction  instead 
of  dilatation. 

CALAMINE— See  Zinc. 

CALAMUS  OIL  (oil  of  sweet  flag) — Distilled  from  the  rhizome 
ofAcorus  calamus,  and  used  in  perfumery,  etc.  It  is  a  thick, 
yellowish,  aromatic  oil,  soluble  in  alcohol  and  ether,  of 
sp.  gr.  about  0*96,  and  refractive  index  about  1*5. 

CALCAREOUS  SPAR— Native  crystallized  calcium  carbonate. 

CALCINATION — Burning  or  incinerating  operation,  such  as 
the  conversion  of  chalk  into  lime  by  burning ;  the  burning 
of  gypsum  to  rid  it  of  water  of  composition  ;  or  of  organic 
matter  such  as  bones,  to  obtain  their  ash.  It  is  a  process 
of  oxidation  largely  resorted  to,  as  a  stage  in  the  separation 
of  metals  from  their  ores. 

Such  operations  are  carried  out  in  the  laboratory  for  the 
most  part  in  crucibles,  and  in  manufacturing  operations  in 
kilns  and  reverberatory  and  other  furnaces. 

CALCITE  (Calcspar)— See  Iceland  Spar. 

CALCIUM  (Ca)  and  its  compounds —Atomic  weight,  40; 
sp.  gr.,  1-85 ;  melting-point,  810°  C.  Calcium  is  not 
met  with  in  nature  in  the  metallic  state,  but  chiefly  in  the 
form  of  carbonate  (CaCO3),  in  minerals  such  as  limestone, 
marble,  calcspar,  and  coral,  in  which  and  other  forms  it  consti- 
tutes a  considerable  part  of  the  earth's  crust. 

In  an  anhydrous  state,  the  sulphate  exists  as  the  mineral 
anhydrite  (CaSO4),  and  in  other  forms  it  exists  as  selenite, 
alabaster,  and  gypsum  (CaSO4,2H2O).  Calcium  is  also 
found  in  nature  in  combination  with  fluorine  as  fluorspar 
(CaF2). 

Calcium  is  a  soft  and  whitish  metal  obtained  in  the 
metallic  state  by  the  electrolysis  of  fused  calcium  chloride. 
When  heated  in  oxygen  to  300°  C.,  it  inflames,  and  the 
lime  which  is  thus  produced  is  fused  by  the  heat. 

Lime  (calcium  oxide,  or  so-called  burnt  lime,  CaO)  is  a 
combination  of  calcium  with  oxygen,  and  is  made  on  a  very 
large  scale  by  burning  limestone  with  coal  in  kilns,  when 
the  carbonate  parts  with  carbon  dioxide  and  leaves  lime  or 
what  is  commonly  known  as  quicklime  behind.  Or  the 
limestone  is  baked  alone  in  furnaces  at  a  heat  sufficiently 
great  to  break  it  up  into  quicklime  and  carbon  dioxide  gas 


CALCIUM  AND  ITS  COMPOUNDS  75 

CALCIUM  (Continued)— 

(CaCO3  =  CaO  +  CO2),  "producer  gas"  (see  Producer  Gas) 
being  used  for  generating  the  heat. 

This  quicklime  (CaO)  is  a  white  and  nearly  infusible 
substance  which,  when  mixed  with  water,  forms  the  white 
powder  known  as  calcium  hydrate  or  slaked  lime  Ca(HO2). 

Lime  is  used  very  largely  in  the  making  of  glass,  mortar, 
and  cement,  and  in  the  preparation  of  lime-wash  and  dis- 
temper paints.  It  is  also  extensively  used  as  the  base  in 
the  manufacture  of  chloride  of  lime  (bleaching-powder)  ; 
also  as  a  dressing  for  skins  to  remove  grease  and  fur,  and 
upon  clayey  soils  to  make  the  land  more  friable. 

Calcium  Carbonate  (CaCO3)  is  almost  insoluble  in  water, 
but  dissolves  readily  when  the  water  contains  carbon  dioxide, 
and  the  so-called  temporary  hardness  of  water  is  due  to  the 
amount  thus  held  in  solution  but  which  is  deposited  when 
the  water  is  boiled.  The  permanent  hardness  of  water  is  due 
to  the  calcium  sulphate  and  other  mineral  salts  which  are 
held  otherwise  in  solution. 

In  the  form  of  arragonite  it  occurs  naturally  in  ortho- 
rhombic  crystals,  and  in  calcspar  as. hexagonal  crystals,  in 
both  of  which  forms  it  can  be  prepared  in  the  laboratory. 
Precipitated  chalk  is  a  well-known  form  of  calcium 
carbonate,  used  in  the  preparation  of  dentifrices  and  pig- 
ments. 

Plaster  of  Paris  is  calcium  sulphate  which  has  been 
deprived  of  part  of  the  water  with  which  it  combines,  by 
heat,  and  its  constitution  is  expressed  by  the  formula 
(CaSO4)2,H2O.  It  has  a  great  affinity  for  recombining 
with  more  water,  with  which  it  sets  into  a  hard  mass, 
and  is  largely  used  for  lining  walls,  moulding  and  other 
purposes. 

On  heating  gypsum  to  about  120°  C.  it  loses  three-fourths 
of  its  water  and  forms  the  hemi-hydrate  (CaSO4JH2O), 
and  it  is  to  the  reconversion  of  this,  by  combination  with 
more  water,  into  the  form  of  the  dihydrate  that  plaster  of 
Paris  is  said  to  owe  its  setting  powers. 

Calcium  Carbide  (sp.  gr.  2-22) — When  ground  lime  or 
chalk  is  strongly  heated  with  coke  in  an  electric  furnace 
to  a  temperature  of  about  3,000°  C.,  calcium  carbide 
(CaC2)  is  produced,  and  this  product  is  now  made  on  a 
large  scale  for  use  in  the  preparation  of  calcium  cyanamide 
and  acetylene  gas  for  lighting  and  other  purposes.  (See 
Acetylene.) 


76  CALCIUM  AND  ITS  COMPOUNDS 

CALCIUM  (Continued)— 

Calcium  Sulphide  (CaS),  a  combination  of  calcium  with 
sulphur,  exhibits  the  property  of  giving  out  a  phosphor- 
escent light  in  the  dark,  and  is  used  in  the  preparation  of 
luminous  paint.  It  is  but  slightly  soluble  in  water,  and 
when  boiled  in  water  it  is  decomposed,  forming  the 
hydroxide  Ca(HO)2  and  the  hydrosulphide  (Ca(HS)2)— a 
product  which  is  used  for  unhairisg  skins  before  tanning 
them. 

Calcium  Chloride  (CaCl2)  can  be  obtained  in  a  crystalline 
form  combined  with  water  (CaCl26H2O),  which  melts  at 
29°  C.  in  its  own  water,  and  when  heated  above  200°  C. 
the  whole  of  the  water  is  dissipated  and  the  anhydrous 
compound  results.  This  is  very  hygroscopic,  and  is  often 
employed  for  drying  gases  by  passing  them  over  and 
through  a  tube  packed  with  it. 

Calcium  chloride  is  extremely  soluble  in  water,  and  is 
produced  in  large  quantities  as  a  by-product  in  many 
manufacturing  operations.  In  one  commercial  form  it  is 
prepared  as  a  solid  containing  from  70  to  75  per  cent. 

Calcium  Nitrate  (Ca(NO3)2.4H2O)  is  a  white  deliquescent 
substance,  soluble  in  water,  and  used  in  pyrotechnics. 

Calcium  Phosphate  (tricalcium  phosphate,  Ca^PO^)  is 
the  most  important  of  the  phosphates  of  calcium,  and  occurs 
in  the  mineral  forms  of  sombrerite  and  coprolites.  When 
acted  upon  by  sulphuric  acid  it  is  decomposed,  forming  a 
mixture  of  another  phosphate  and  calcium  sulphate — 

Ca3(P04)2  +  2H2SO4=  CaH4(P04)2  +  2CaSO4. 

This  mixture  is  known  commercially  as  superphosphate  of 
lime,  and  is  made  from  bones,  which  contain  calcium 
phosphate.  (See  Phosphorus.) 

In  combination  with  phosphoric  acid  and  calcium  fluoride, 
calcium  is  also  found  in  the  mineral  known  as  apatite. 

There  are  commercial  preparations  of  calcium  sulphite 
(in  powder  and  tablets),  ferrocyanide,  and  the  so-called  acid 
phosphate  (Ca(H2PO4)2),  a  preparation  that  is  used  as  a 
substitute  for  cream  of  tartar  in  making  "self-raising 
flour,"  and  baking  and  egg  powders. 

Calcium  Fluoride  (CaF2)  is  found  as  fluorspar  in  crys- 
talline cubes  in  Derbyshire  and  Cumberland,  and  is  used 
as  a  flux  in  the  reduction  of  metals.  When  heated  with 
strong  sulphuric  acid,  hydrofluoric  acid  and  calcium  sul- 
phate are  produced.  (See  Fluorine.) 


CALCIUM  AND  ITS  COMPOUNDS  77 

CALCIUM  (Continued)— 

Bleaching-powder,  or  so-called  chloride  of  lime,  is  manu- 
factured on  a  large  scale  by  the  action  of  chlorine  gas  upon 
moist  slaked  lime  until  the  product  contains  about  from 
35  to  38  per  cent,  of  chlorine,  the  interaction  that  takes 
place  being  represented  by  the  equation — 

Ca(HO)2  +  C12  =  CaOCl2  +  H2O, 

although  there  is  always  an  excess  of  lime  left  in  the 
resulting  product. 

When  treated  with  water  this  substance  breaks  up  into 
calcium  hypochlorite  (which  has  been  isolated)  and  calcium 
chloride — 

2CaOCl2  =  CaCl2  +  CaCl2O2. 

Bleaching-powder  is  largely  employed  in  the  arts,  the  goods 
to  be  bleached  being  first  of  all  dipped  into  a  dilute  solution 
of  the  substance  and  then  passed  through  a  dilute  acid 
solution,  chlorine  gas  being  thus  liberated  within  the  fibres 
of  the  fabrics,  which  are  bleached  thereby. 

Bleaching  by  chlorine  is  really  a  process  of  oxidation,  as 
the  chlorine  decomposes  water  in  the  act,  liberating  nascent 
oxygen ;  thus  indigo  blue  is  converted  by  chlorine  into  an 
orange-red  non -tinctorial  principle  named  isatin.  It  is  also 
used  on  a  considerable  scale  as  a  sanitary  reagent. 

Calcium  Cyanamide  or  Nitro-lime  (CaCN2) — A  substance 
produced  by  strongly  heating  calcium  carbide  in  nitrogen 
gas,  the  heat — about  800°  to  900°  C. — being  produced  by 
an  electric  current  passing  through  carbon  resistances 
placed  in  the  powdered  carbide.  The  output  of  this  pro- 
duct in  1917  was  900,000  tons.  The  product  consists  of 
about  f  cyanamide  and  contains  from  20  to  22  per  cent, 
nitrogen,  which  is  transformed  by  a  series  of  changes  into 
ammonia  when  the  substance  comes  into  contact  with  water, 
thus  explaining  its  value  as  a  fertilizer.  When  pure  it  is 
white  and  crystalline. 

Calcium  Acetate  (Ca(C2H?O2)2H2O)  is  a  white  crystalline 
body,  soluble  in  water,  and  is  employed  in  the  manufacture 
of  acetone  and  acetic  acid. 

Calcium  Bisulphite  (Ca(HSO3)2),  which  is  soluble  in 
water,  is  prepared  in  the  form  of  a  yellowish  liquid,  having 
a  strong  odour  of  sulphur  dioxide  by  the  action  of  that  gas 
on  calcium  hydroxide,  being  generally  sold  of  8°  B  strength. 
It  is  largely  used  in  the  manufacture  of  wood  pulp ;  also  as 
an  antichlor,  as  a  preservative,  and  for  bleaching  sponges. 


CA  LCIUM—CA  LI  CHE 


CALCIUM  (Continued)— 

Calcium  Phosphide — See  Phosphorus. 

Calcium  Tungstate  (CaWO4)  is  a  crystalline  substance, 
insoluble  in  water,  used  in  making  luminous  paint. 

CALCULI  (Urinary) — Consist  of  or  contain  uric  acid,  ammo- 
nium and  other  urates,  calcium  oxalate,  calcium  phosphate, 
the  double  phosphate  of  ammonium  and  magnesium, 
xanthine  and  cystine,  generally  constructed  round  a 
nucleus  of  some  foreign  substance,  such  as  blood-cor- 
puscles, etc. 

CALICHE — This  impure  soda  nitre  (sodium  nitrate)  occurs  in 
almost  unlimited  quantities  in  South  America  and  more  par- 
ticularly in  the  district  of  Atacama  in  Peru. 

It  is  cheaper  than  potassium  nitrate  and  yields  9  per  cent, 
more  nitric  acid  when  employed  for  the  manufacture  of 
sulphuric  acid. 

The  following  analyses  have  been  published  : 


No.  i,  White  Caliche. 

No.  2,  Brown  Caliche. 

Sodium  nitrate     ... 

Per  Cent. 
70*62 

Per  Cent. 
60-97 

„       iodate 

I-QO 

0'73 

„        chloride  ... 

22'39 

16-85 

„       sulphate... 

I  -80 

4'56 

Calcium  sulphate 

0-87 

I-3I 

Magnesium  sulphate 

0-5I 

5'88 

Insoluble  matter  ... 

0-92 

4-06 

Water        ... 

0'99 

5*64 

lOO'OO 

1  00  '00 

It  is  often  found  covered  by  deposits  of  costra,  which  is  a 
harder  saline  deposit  not  without  value,  and  the  table  on 
the  opposite  page  gives  analyses  which  have  been  pub- 
lished of  it,  and  the  soda  nitre  found  beneath  it  in  the 
basin  of  the  Loa  (Chili). 

Sometimes  the  soda  nitre  is  found  in  an  almost  pure  state 
and  it  can  be  made  to  contain  from  95  to  96  per  cent,  by 
crushing,  dissolving  in  water,  and  recrystallizing.  Some 
3,000,000  tons  are  extracted  annually.  Apart  from  what  is 


CA  LICHE—CA  MPHOR 


79 


CALICHE  (Continued)— 

used  in  the  alkali  trade,  there  is  a  much  larger  consumption 
as  a  fertilizing  agent.     (See  Fertilizer.) 


Soda  Nitre. 

Costra. 

M 

(2) 

Sodium  nitrate 

5*'5° 

49-05 

18-60 

,,       sulphate    ... 

8-09 

9-02 

16-64 

„        chloride     ... 

22-08 

28-95 

33-80 

Potassium  chloride 

8'55 

4'57 

2-44 

Magnesium      „ 

o'43 

1-25 

1-62 

Calcium  carbonate 

0'12 

0-15 

0-09 

Silica  and  iron  oxide 

0-90 

2-80 

3*oo 

Sodium  iodide 

traces 

traces 

— 

Insoluble  matter    .  .  . 

6-00 

3-18 

20-10 

CALOMEL— See  Mercury. 

CALORIMETER — A  device  for  measuring  the  heat  generated 
by  burning  bodies  or  by  chemical  interactions. 

CALOKIZING — A  process  for  the  impregnation  of  steel,  iron, 
copper,  brass,  etc.,  with  aluminium,  forming  a  homogeneous 
alloy  to  a  certain  depth,  effected  by  heating  in  a  reducing 
atmosphere  with  a  mixture  containing  finely  divided  alu- 
minium, thus  giving  a  protection  strongly  resistant  to  the 
oxidizing  action  of  high  temperature. 

CALORY— See  Heat,  p.  244: 


CAMPHENE  (C10H16)  is  a  colourless,  crystalline   terpene   of 
sp.  gr.  0-8446  and  melting-point  49*5°  C.,  which  boils  at 


157°  C.  It  is  soluble  in  alcohol  and  ether,  is  prepared  by 
treating  pinene  hydrochloride  with  alcoholic  potash,  and 
is  used  in  making  camphor  substitutes. 

CAMPHOR  (Ci0H16O)  is  a  well-known  natural  product  of 
characteristic  odour  formed  in  camphor- trees  (Laiwus 
camphora)  which  grow  in  China,  Formosa,  and  Japan,  and  is 
obtained  by  distillation  of  the  wood  and  all  parts  of  the  trees. 
The  total  output  of  camphor  from  Japan  and  Formosa  for 
the  year  ended  March  31,  1918,  was  4,854,000  kilos,  or 
approximately  4,777  tons. 

It  is  accompanied  by  oil  of  camphor,  a  hydrocarbon  allied 
in  composition  with  turpentine.      Camphor  is  soluble  in 


8o  CAMPHOR— CAMPHOR  OIL 

CAMPHOE  (Continued)— 

alcohol  and  ether,  crystallizes  in  glistening  prisms,  has  a 
sp.  gr.  of  0-986  to  0-996,  melts  at  175°  C.,  and  can  be 
readily  sublimed.  By  reduction  it  yields  cymene  (C10H14), 
and  by  oxidation  with  nitric  acid  it  yields  camphoric  acid 
(C10H16O4).  Considerable  quantities  of  camphor  are  made 
synthetically  from  pinene  (C10H16)  (the  chief  constituent  of 
German  and  American  turpentine).  Pinene  is  first  of  all 
converted  into  solid  hydrochloride,  a  white  crystalline  sub- 
stance having  itself  a  camphor-like  odour,  and  this  is 
changed  into  camphene  by  ammonia,  pyridine,  or  any  one 
of  a  number  of  available  methods  for  removing  the  HC1 
constituent.  The  camphene  thus  prepared  (also  a  solid 
body)  is  next  hydrated  with  borneol  (C10H17.OH)  by  heating 
glacial  acetic  acid  and  about  2  per  cent,  of  sulphuric  acid, 
and  the  borneol  is  finally  transformed  into  artificial  camphor 
by  oxidation  with  air,  oxygen,  ozone,  or  other  agent,  or  by 
dehydrogenation  brought  about  by  passing  the  vapour  of 
the  borneol  over  finely  divided  copper  heated  to  from  300° 
to  330°  C.,  thus  splitting  it  up  into  hydrogen  and  camphor. 
Camphor  is  largely  used  in  the  arts  and  industries,  also  as  a 
vermifuge  and  in  medicine. 

The  only  observable  difference  between  the  natural  and 
the  artificial  camphor  is  that  the  former  rotates  the  polarized 
light  ray  while  the  latter  is  optically  inactive. 

CAMPHORIC  ACID  (C10H16O4)  is  prepared  by  the  oxidation 
of  camphor  (C10H16O)  with  strong  nitric  acid  and  is  a 
white  crystalline  body,  which  melts  at  208°  C.,  is  slightly 
soluble  in  cold,  but  fairly  so  in  hot  water,  and  easily  dis- 
solved by  alcohol.  It  somewhat  resembles  phthalic  acid, 
and  some  six  modifications  of  it  are  known — viz.,  four  opti- 
cally active  and  two  optically  inactive  forms.  It  is  stated 
to  be  used  in  making  celluloid  articles.  (See  Racemic.) 

CAMPHOR  OIL  is  a  by-product  obtained  in  the  fractional  dis- 
tillation of  crude  camphor  oil  from  Cinnamomum  camphora, 
and  is  a  mixture  of  pinene,  cineol,  and  phellandrene  con- 
taining some  camphor  in  solution.  It  has  a  sp.  gr.  of 
about  0-87  to  i -oo,  is  soluble  in  alcohol  and  ether,  and  is 
used  as  a  substitute  for  turpentine  and  for  illumination. 

Camphor  Wood  Oil  is  sometimes  supplied  in  the  form  of  a 
yellow  crystalline  mass,  soluble  in  alcohol  and  ether,  but 
otherwise  as  a  liquid,  and  is  furnished  by  dry  distillation  of 
the  camphor-tree  wood  (Dryobalanops  aromatica).  It  is  used 
in  perfumery. 


CAMPHOR  OIL—CAOUTCHOUC  81 

CAMPHOR  OIL  (Continued)— 

From  a  recently  published  paper  it  is  gleaned  that  the 
oil  distilled  from  the  leaves  of  Indian-grown  trees  contains 
pinene,  dipentene,  cineol,  terpineol,  and  caryophyllene,  but 
cineol  is  stated  to  be  absent  from  the  oil  distilled  from  the 
twigs.  The  wood  oil  is  stated  to  be  similar  to  that  produced 
elsewhere :  it  contains  safrol,  eugenol,  carvocrol,  and  other 
substances,  but  not  cineol. 

Camphor  oil  is  used  in  Japan  as  raw  material  for  the 
manufacture  of  heliotropin  from  the  safrol  contained  in  it. 

CANADA  BALSAM— See  Balsams. 
CANANGA  OIL— See  Hang  Hang  Oil. 
CANAUBA  WAX— See  Waxes. 
CANDALETTA  WAX— See  Waxes. 

CANDLES  are  made  of  solid  fatty  acids,  with  or  without 
admixture  of  waxes  such  as  paraffin  wax  or  ozokerite. 
The  addition  of  wax  gives  hardness  to  the  candles.  (See 
also  Fats.) 

CANDLE-NUT  OIL  (Lumbang  oil) — Made  in  the  Philippine 
Islands  from  the  fruits  of  the  candleberry  tree  (Aleuritis 
moluccana).  The  kernels  yield  an  oil  making  up  637  per 
cent,  of  their  weight.  It  is  liquid  at  18°  C.,  of  pale  yellow 
colour,  has  a  sp.  gr.  of  0-925,  saponification  value  of  190  to 
195,  iodine  value  136  to  140,  and  is  used  as  an  illuminant 
and  in  soap-making,  but  is  not  edible  on  account  of  its 
purgative  properties. 

CANNABIS  INDICA  (Indian  hemp) — From  the  flowering  tops 
of  Cannabis  sativa. 

CANNABIS  SATIVA— Common  hemp. 

CANTHARIDES  or  SPANISH  FLIES  (Lytta  vesicatoria)— 
Coleopterous  insects  used  in  medicine  for  vesicating  pur- 
poses in  the  form  of  tinctures  and  plasters,  also  for  com- 
pounding hair  tonics.  The  active  principle  is  a  poisonous 
crystalline  substance  named  cantharidin  (C^H^O^  which 
is  prepared  from  these  insects  or  from  Mylabns  cichoni  by 
digestion  with  ether  or  alcohol,  or  a  mixture  of  these  two 
solvents. 

CAOUTCHOUC— See  Rubber. 


82  CAPILLARY  ATTRACTION— CARBAMINES 

CAPILLARY  ATTRACTION  results  from  the  adhesion  or 
cohesion  of  fluids  to  solids  as  instanced  by  a  burning  night- 
light  in  which  the  melted  wax  flows  to  the  burning  wick. 
Water  is  supplied  to  the  roots  and  stems  of  growing  plants 
by  capillary  attraction. 

CAPRIC  ACID  (C10H20O2)— A  member  of  the  normal  fatty 
acids,  present  in  cow's  and  goat's  milk  and  cocoa-nut  oil, 
and  can  be  formed  by  the  oxidation  of  oleic  acid.  It  melts 
at  31°  C.,  and  is  soluble  in  alcohol. 

CAPROIC  ACID  (CgH12O2)— A  member  of  the  normal  fatty 
acids,  contained  in  goat's  milk  and  cocoa-nut  oil,  and  often 
forms  one  of  the  products  of  the  oxidation  of  higher  acids 
of  the  same  series.  It  is  an  oily  body  of  sp.  gr.  0-931  at 
15°  C.,  with  a  sudorific  odour,  and  is  soluble  in  alcohol  and 
ether. 

CAPRYLIC  ACID  (C8H16O2)— A  fatty  acid  of  unpleasant  odour 
contained  in  cow's  milk,  cocoa-nut  oil,  Lemberg  cheese, 
and  some  fusel-oils.  It  has  a  sp.  gr.  of  0-9185,  melts  at 
1 6°  C.,  and  is  soluble  in  water,  alcohol,  and  ether. 

CAPSICUM  (Cayenne  pepper) — Prepared  from  the  dried  ripe 
fruit  of  Capsicum  fastigiatum.  Though  used  as  a  condiment 
in  the  main  it  is  also  employed  medicinally  as  a  counter-agent 
to  the  relaxing  effects  of  heat  and  also  to  check  the 
drink-craving  of  dipsomaniacs.  The  pungent  principle  of 
Spanish  pepper  (the  fruit  of  Capsicum  annuum)  is  said  to  be 
an  alkaloid  named  capsaicin  (C18H29O3.N).  The  name 
"  capsicine "  has  been  applied  in  America  to  an  oleo- 
resinous  extract  from  Capsicum  baccatum. 

CARAGHEEN  MOSS— An  Irish  moss  or  alga  used  as  a  food. 

CARAMEL — A  dark-coloured  substance,  soluble  in  water,  made 
from  cane-sugar  by  heating  it  above  its  melting-point 
(160°  C.)  up  to  about  170°  to  180°  C.,  when  it  loses  two 
molecules  of  water  and  caramelan  (C12H18O9)  is  formed — a 
brown  colouring  matter  which  is  the  characteristic  principle 
of  caramel  or  sugar  dye. 

CARAWAY — The  dried  seeds  of  Carum  carvi  yields  a  thin, 
nearly  colourless  oil  (soluble  in  alcohol  and  ether),  contain- 
ing carvone  and  dextro-limonene.  Sp.  gr.,  0-907  to  0-915  ; 
optical  rotation,  +75  to  +85;  refractive  index,  1-4867  to 
1-4970.  It  is  used  in  medicine  and  in  flavouring. 

CARBAMIDE— See  Urea. 

CARBAMINES — Basic  isocyanides,  such  as  methyl  isocyanide 
(CH3NC). 


CA  RBA  ZOLE—CA  RBOHYDRA  TES  83 

CARBAZOLE  (C12H9N  or  (C6H4)2NH),  the  imide  of  di- 
phenyl,  is  a  constituent  of  coal-tar  and  crude  anthracene.  It 
is  a  white,  crystalline  substance  which  melts  at  238°  C.,  is 
readily  sublimable,  and  can  be  formed  by  passing  the 
vapour  of  diphenylamine  through  red-hot  tubes. 

A  recently  patented  process  for  its  manufacture  consists 
in  heating  the  crude  article  with  an  alkali  metal  or 
hydroxide  in  the  presence  of  an  indifferent  solvent,  such  as 
naphthalene  or  toluol,  under  pressure,  and  at  a  temperature 
below  the  melting-point  of  the  alkaline  carbonate.  The 
solvent  is  subsequently  removed,  and  the  alkali-carbazole 
decomposed  by  boiling  with  water. 

Carbazole  is  soluble  in  alcohol  and  ether,  but  insoluble 
in  water,  and  is  used  in  the  manufacture  of  dyestuffs.  (See 
Imides.) 

CARBIDES — Compounds  of  carbon  with  metals  such  as 
calcium  carbide  and  cast-iron,  a  quality  of  which  can  be 
made  corresponding  with  the  formula  CFe2. 

CARBOHYDRATES  constitute  a  large  body  of  organic  com- 
pounds built  up  for  the  most  part  of  carbon  with  hydrogen 
and  oxygen  in  the  proportion  in  which  they  exist  in  water — 
hence  the  name.  They  include  sugars,  starches,  and  cellu- 
loses, but  there  are  other  carbohydrates  such  as  rhamnose 
(C6H12O5),  in  which  the  hydrogen  and  oxygen  constituents 
are  nol  present  in  the  water  proportions. 

According  to  one  grouping  now  observed,  they  are 
divided  into  three  great  classes — viz.,  the  Monosaccharoses, 
including  arabinose  (C5H10O5),  and  glucose  and  fructose, 
which  are  isomeric  bodies  (C6H12O6) ;  the  Bi  and  Trisac- 
charoses,  which  may  be  viewed  as  anhydrides  of  the  first 
group  (that  is,  devoided  of  i  or  2  molecules  of  water  re- 
spectively), such  as  cane-sugar  (CjnHaaO^,  which  must  then 
be  regarded  as  the  anhydride  of  glucose ;  and  the  Poly- 
saccharoses  or  polyoses,  including  the  starches  and  the 
celluloses,  from  which  a  monosaccharose  can  be  obtained 
by  hydrolysis. 

The  compounds  of  the  first  class  are  sweet,  are  all 
soluble  in  water  and  do  not  crystallize,  at  any  rate  not  very 
well ;  those  of  the  second  class  are  also  sweet,  and  crystal- 
lize ;  whilst  the  members  of  the  third  class  are  not  sweet, 
are  not  soluble  in  water,  and  are  non-crystalline. 

The  simple  sugars  combining  the  chemical  properties 
of  alcohols  and  aldehydes  are  now  termed  aldhoses,  while 
those  which  are  at  the  same  time  like  alcohols  and  ketones 
are  styled  ketoses. 


84  CA  RBOHYDRA  TES—CA  RBON 

CARBOHYDRATES  (Continued)— 

Many  of  these  substances  are  described  under  their  several 
names.  As  a  class,  the  carbohydrates  char  when  heated 
strongly,  and  give  off  an  odour  of  burnt  sugar.  (See  also 
Saccharoses,  Starches,  and  Sugar.) 

CARBOLIC  ACID  —  Liquid  commercial  carbolic  acid  is  a 
straw-coloured  liquid  of  about  ro8  sp.  gr.,  and  is  a  mixture 
of  phenol  (C6H5OH)  and  cresol  (C7H7OH)  with  some  other 
associated  substances,  all  of  which  are  termed  "  tar  acids." 
It  is  separated  from  the  cruder  coal-tar  distillates  from  which 
it  is  prepared,  by  extraction  with  caustic  soda,  the  saponi- 
fied liquid  thus  obtained  being  afterwards  treated  with  sul- 
phuric acid,  which  combines  with  the  soda  and  sets  free 
the  "  tar  acids."  (See  Phenols.) 

CARBON  AND  ORGANIC  MATTERS— 

Carbon  (C) — atomic  weight,  12;  melting-point,  above 
3,600°  C. — is  well  known  in  the  three  forms  of  the  diamond, 
graphite  (plumbago),  and  charcoal.  It  is  also  found  widely 
distributed  in  nature,  not  only  as  a  constituent  of  animal 
and  vegetable  tissues,  and  in  the  air  in  the  form  of  carbon 
dioxide  (CO2),  but  also  in  combination  as  calcium  carbonate 
(CaCO3)  in  the  rocks  known  as  limestone  and  dolomite. 
Diamonds  are  found  in  many  deposits  in  Brazil,  India, 
South  Africa,  and  elsewhere,  and  are  for  the  most  part 
colourless,  but  sometimes  tinged  with  various  colourings. 
Minute  diamonds  have  been  made  artificially  on  a  very 
small  scale,  and  proved  to  have  the  same  composition  as 
the  natural  diamonds. 

When  strongly  ignited,  diamonds  burn  up  in  the  presence 
of  oxygen  into  carbon  dioxide  (CO2),  just  as  charcoal 
does  at  a  lower  temperature,  thus  proving  them  to  consist 
of  carbon. 

Graphite  is  found  plentifully  in  nature  in  Canada,  Japan, 
Siberia,  Spain,  California,  Ceylon,  and  elsewhere,  including 
Borrowdale  in  Cumberland,  where  it  is  used  in  the  pre- 
paration of  pencils.  It  is  a  shiny,  soft,  nearly  black  sub- 
stance consisting  mainly  of  carbon,  and  on  account  of  its 
refractory  character  it  is  used  for  the  manufacture  of  so- 
called  plumbago  crucibles — that  is,  crucibles  made  of 
fireclay  mixed  with  graphite — and  arc-light  carbons.  It 
is  also  employed  as  a  polish  and  coating  (blackleading)  for 
iron  articles  to  prevent  rusting,  and  as  a  paint  pigment. 

Carbon  ic  also  known  in  impure  form  as  coke,  lamp- 
black, and  animal  charcoal  (bone-black),  and  this  last- 
named  substance  is  used  in  refining  sugar,  glycerine,  fats, 


CARBON  AND  ORGANIC  MATTERS  85 

CARBON  AND  ORGANIC  MATTERS  (Continued)— 

etc.,  to  decolorize  the  solutions,  having  the  property  of 
taking  up  many  kinds  of  colouring  matters.  In  this 
property,  birch  charcoal-dust  is  stated  to  be  equally  efficient. 
Animal  charcoal  prepared  from  bones  contains  about  81  per 
cent,  of  calcium  and  magnesium  phosphates  and  calcium 
fluoride,  from  7  to  8  per  cent,  of  calcium  carbonate  and 
other  salts,  and  from  10  to  n  per  cent,  of  carbon. 

Most  of  the  carbon  black  used  in  the  United  States  of 
America  in  the  preparation  of  inks,  polishes,  pigments,  and 
the  rubber  industries,  is  now  made  by  the  incomplete  com- 
bustion of  natural  gas  in  air.  It  is  of  a  velvety  black 
character,  but  only  a  small  percentage  of  the  total  carbon 
is  recovered  (by  collection  upon  a  metallic  surface  held  in 
contact  with  the  flame) — namely,  from  ij  to  3^  per  cent. 

Charcoal  has  the  property  of  absorbing  gases  very  readily, 
wood  and  peat  charcoal  being  superior  in  this  respect 
to  animal  charcoal.  The  absorptive  power  of  wood  char- 
coal is  notably  increased  by  prolonged  heating,  and  the 
denser  charcoals — notably  those  from  palm-nut,  cocoa-nut, 
and  fruit  stones — are  the  most  efficient  gas  absorbents. 
The  following  table  shows  the  capacity  of  absorption  of 
various  gases  by  boxwood  charcoal : 

Ammonia  gas         ...         ...         ...  90  volumes 

Hydrochloric  acid  gas      85 

Sulphur  dioxide  gas          65 

Hydrogen  sulphide  gas 55 

Carbon  dioxide  gas  35 

Oxygen  gas  9-25 

(See  Adsorption.) 

Water  is  not  adsorbed  by  charcoal,  but  absorbed  or  held 
by  capillary  action,  and  the  adsorptive  power  of  charcoal 
varies  with  the  method  of  its  preparation  within  very  wide 
limits.  The  adsorption  of  oxygen  by  charcoal  is  considered 
due  to  a  surface  action,  the  product  being  a  kind  of  carbon 
oxide  which  upon  heating,  breaks  up  into  carbon  monoxide 
and  carbon  dioxide,  so  that  it  has  to  be  regarded  as  an 
intermediate  compound  in  the  combustion  of  the  charcoal. 

"Char"  does  not  only  adsorb  colour  from  complex 
solutions,  but  will  retain — sometimes  with  great  avidity — 
many  mineral  and  organic  compounds,  such  as  the  alkaloids, 
for  which,  indeed,  purified  animal  black  is  an  antidote. 

All  vegetable  matters  consist,  in  part,  of  carbon  in  chemical 
combination  with  hydrogen  and  oxygen,  and  when  they  are 
burned  with  an  insufficient  quantity  of  air  or  oxygen,  a 


86  CARBON  AND  ORGANIC  MATTERS 

CARBON  AND  ORGANIC  MATTERS  (Continued)— 

mass  of  "  char,"  or  carbon,  remains  behind.  For  example, 
when  wood  is  burned  in  a  smothered  sort  of  way — that  is, 
with  an  insufficient  quantity  of  air  or  oxygen — a  part  of 
it  is  left  behind  in  the  form  of  wood-charcoal ;  in  fact,  that 
is  how  charcoal  is  prepared. 

Of  course,  if  enough  oxygen  or  air  is  supplied  to  burning 
wood  or  coal,  all  the  carbon  becomes  consumed  by  entering 
into  combination  with  the  oxygen,  and  only  the  ash  is  left. 
This  ash  consists  of  mineral  matters  which  were  present  in 
the  wood  and  coal  before  burning. 

Vegetable  Matters — There  are  an  immense  number  of 
vegetable  substances  and  products,  such  as  sugar,  rosin, 
starch,  gum,  linseed  oil,  castor  oil,  cocoa-nut  oil,  various 
fats,  essential  oils,  and  colouring  matters,  all  of  which 
consist  of  chemical  compounds  of  carbon  with  hydro- 
gen and  (mostly)  oxygen.  All  these  products  of  vegetable 
life  are  built  up  by  chemical  processes  which  take  place  in 
their  living  organisms,  and  are  derived  from  the  carbon 
dioxide  absorbed  from  the  soil  and  air  by  their  roots  and 
other  parts — stomata,  or  small  openings  on  the  lower  surface 
of  leaves — and  this  fact  demonstrates  very  forcibly  the  im- 
portance of  that  substance  as  a  constituent  of  the  atmo- 
sphere. Many  of  these  products  can  be  built  up  artificially 
by  means  of  synthetical  processes,  showing  that  these 
natural  processes  are  essentially  of  the  same  order  as  other 
chemical  processes,  although  very  complicated  and  at 
present  imperfectly  understood.  Amongst  the  substances 
that  have  been  produced  by  chemists  may  be  mentioned 
formaldehyde,  urea,  alcohol,  glycerine,  tartaric  acid,  indigo- 
tine,  vanillin,  alizarin,  indiarubber,  and  coumarin  (the 
odoriferous  principle  of  the  Tonka  bean) ;  also  many 
synthetical  perfumes,  the  manufacture  of  which  has  become 
an  important  industry. 

We  may  well  be  excited  to  wonder  by  the  marvellous 
extent  and  nature  of  the  structures  (forms),  the  tissues,  the 
colouring  matters  and  the  products  that  characterize  vege- 
table life,  all  of  which  are  built  up  out  of  the  constituents 
of  the  soil  and  the  air  by  the  living  agencies  contained  in 
their  seeds.  These  wonderful  processes  of  nature  may  be 
compared  with  the  determining  force  that  causes  many 
salts  in  a  state  of  solution  to  crystallize  out  therefrom  in 
such  beautiful  geometrical  or  symmetrical  forms  as 
referred  to  in  another  section. 

Animal  Matters — Other  organic  compounds  are  found 
to  exist  in  all  parts  of  the  flesh,  the  brains  and  other  parts 


CARBON  COMPOUNDS  87 

CARBON  AND  ORGANIC  MATTERS  (Continued)— 

of  animals,  but  sometimes  phosphorus  is  also  found  in 
association,  and  these  organic  compounds  are  even  more 
complex.  By  animals  we  mean  not  only  human  beings, 
but  all  beasts,  birds,  fishes,  and  insects. 

Compounds,  of  which  carbon  forms  an  important 
constituent,  are  generally  termed  organic,  and  all  of  them 
are  combustible — that  is  to  say,  they  can  be  burned  up  if 
heated  sufficiently  in  the  presence  of  plenty  of  air  or  oxygen. 

CARBON  COMPOUNDS— Carbon  forms  two  compounds  with 
oxygen — viz.,  carbon  monoxide  (CO)  and  carbon  dioxide 
(CO2).  The  former  is  produced  whenever  carbon  is  burned 
with  an  insufficient  supply  of  oxygen  to  convert  it  into  the 
dioxide,  and  may  be  prepared  in  the  laboratory  by  passing 
a  stream  of  the  carbon  dioxide  gas  over  charcoal  heated 
to  redness:  CO2  +  C  =  2CO.  It  is  a  colourless  gas  of 
poisonous  properties,  but  slightly  soluble  in  water, 
i  volume  of  which  at  o°  C.  dissolves  0-0328  volume  of  the 
gas,  and  it  is  utilized  in  a  process  for  the  manufacture  of 
the  metal  nickel.  (See  Nickel.)  It  occurs  at  times  in  coal- 
mines, and  is  known  as  white-damp.  (See  Safety  Lamp.) 

Carbon  dioxide  is  elsewhere  referred  to  as  a  constant 
constituent  of  the  atmosphere  and  as  a  product  of  respira- 
tion. It  is  the  gaseous  product  which  is  obtained  whenever 
carbon  is  burned  with  a  sufficiency  of  oxygen,  and,  like 
carbon  monoxide,  is  a  colourless  gas  which  admits  of  con- 
densation into  the  liquid  and  solid  forms.  It  can  readily 
be  produced  by  the  action  of  acids  upon  carbonates,  such 
as  calcium  carbonate  (chalk  and  marble),  and  when  hydro- 
chloric acid  is  used  in  this  process  the  change  that  takes 
place  is  represented  as  follows : 

CaCO3  +  2HC1  =  CaCl2  +  H2O  +  CO2 

— that  is  to  say,  the  carbon  dioxide  gas  escapes  in  a  brisk 
effervescence,  calcium  chloride  being  left  behind  in  solution. 
One  volume  of  water  at  o°  C.  dissolves  1713  volume  of 
the  gas,  which  is  employed  commercially  in  various  ways, 
both  as  a  gas  and  in  liquefied  form  ;  amongst  other  applica- 
tions for  impregnating  water  under  pressure  (making  what 
is  called  soda-water),  as  a  fire  extinguisher  and  for  re- 
frigeration. 

It  is  one  of  the  constituents  of  what  is  called  black-damp 
or  choke-damp  by  coal-miners,  and  often  occasions  loss  of 
life  in  mines  after  explosions. 

Carbonic  Acid  (H2CO3) — This  combination  of  carbon  di- 
Qxide  with  water  (CO2  +  H2O  =  H?CO3)— although  itself  ant 


88  CARBON  COMPOUNDS 

CARBON  COMPOUNDS  (Continued)— 

unstable  body  —  forms  with  bases  a  great  series  of  well- 
defined  compounds  known  as  carbonates.  Thus,  by  com- 
bination with  the  so-called  alkalies  and  alkaline  earths,  we 
get  the  following  series  : 

Sodium,  potassium,  and  ammonium  carbonates  (Na2CO3, 
K2CO3,  and  (NH4)2CO3),  all  of  which  are  soluble  in  water 
and  calcium,  barium,  and  magnesium  carbonates  (CaCO3, 
BaCO3,  and  MgCO3),  all  of  which  are  insoluble  in  water 
or.  practically  so. 

Carbon  also  combines  with  sulphur  to  form  the  evil- 
smelling  compound  known  as  carbon  disulphide  (CS2), 
which  may  be  prepared  by  passing  the  vapour  of  sulphur 
over  red-hot  carbon,  the  CS2,  which  is  volatile,  being  sub- 
sequently condensed  in  properly  cooled  vessels.  Carbon 
disulphide  is  a  colourless  liquid  of  sp.  gr.  i  '27  ;  it  is 
manufactured  on  a  considerable  scale,  and  employed  as 
a  solvent  of  caoutchouc,  fats  and  other  substances,  also 
in  processes  for  extraction  of  essential  oils  and  perfumes, 
etc. 

There  are  many  organic  compounds  which  are  composed 
of  carbon  and  hydrogen  only,  termed  hydrocarbons,  in- 
cluding such  substances  as  methane  or  marsh-gas  (CH4), 
acetylene  (C2H2),  benzene  (C6H6),  naphthalene  (C10H8), 
and  turpentine  (C10H16). 

Cyanogen  (C2N2)  consists  of  carbon  and  nitrogen  only. 

Many  others  contain  oxygen  in  addition  to  carbon  and 
hydrogen,  and  there  may  be  named  as  examples,  alcohol 
(C2H6O),  glycerine  (C3H8O3),  acetic  acid  (C2H4O2),  phenol 
(C6HCO),  and  the  carbohydrates. 

Another  class  consists  of  carbon,  hydrogen,  and  nitrogen, 
including  prussic  or  hydrocyanic  acid  (CHN)  and  aniline 
(C6H?N),  whilst  yet  another  class  contains  oxygen  in 
addition  to  these  three  elements,  such  as  urea  (CH4N2O), 
indigotm(C16H10N2O2),  morphine  (C17H19NO3),and  quinine 


2n2422. 

There  are  still  more  complicated  organic  substances  in 
which  other  elements  exist  in  combination  with  carbon, 
and  one  or  more  of  those  already  mentioned,  such  as  sul- 
phur, phosphorus,  chlorine,  bromine,  and  iodine. 

The  chief  solid  parts  of  the  living  tissues  of  animals  are 
composed  of  so-called  albumins  or  albuminoids  containing 
from  527  to  54-5  per  cent,  carbon  ;  7  to  7*3  per  cent. 
hydrogen;  20-9  to  23-5  per  cent,  oxygen;  15  to  18  per 
cent,  nitrogen  ;  and  075  to  5  per  cent,  sulphur,  approxi- 
mately represented  by  the  formula  C72H112Nj8SO22. 


CARBONATES—"  CARBORAFFIN "  89 

CARBONATES— See  Carbon. 

CARBON  DIOXIDE— See  Carbon. 

CARBON  DISULPHIDE— See  Carbon. 

CARBON  ELECTRODES,  as  used  for  electric  furnace  work, 
are  of  several  kinds,  some  being  made  of  graphite,  others 
of  carbon  derived  from  the  baking  of  coal-tar  pitch  having 
a  melting-point  of  from  150°  to  200°  F.  A  good  pitch  of 
this  character  loses  nearly  all  its  volatile  matter  at  600°  F. 
Anthracite  coal  is  one  of  the  best  materials  for  the  making 
of  amorphous  carbon  electrodes. 

The  electrodes  are  formed  by  ramming  the  material  into 
the  mould,  wherein  it  is  calcined. 

CARBONIFEROUS— The  oldest  or  Palaeozoic  system  of  geo- 
logical formation,  including  the  coal-measures. 

CARBON  MONOXIDE— See  Carbon. 

CARBON  TETRACHLORIDE  (CC14)— A  thin,  colourless, 
poisonous  liquid,  of  pungent  aromatic  odour,  which  boils 
at  77°  C.,  prepared  from  chloroform  or  from  carbon  disul- 
phide  by  the  action  of  chlorine.  It  has  a  sp.  gr.  of  1-5835, 
and  is  largely  used  as  a  solvent  for  fats,  in  fire  extinguishers, 
and  making  cleaning  compounds.  Experience  has  shown 
that  it  is  dangerous  to  use  carbon  tetrachloride  fire  ex- 
tinguishers in  confined  spaces  where  users  cannot  avoid 
breathing  the  poisonous  fumes  that  are  produced  by  its 
decomposition. 

CARBONYL  CHLORIDE  (Phosgene)  (COC12)  is  produced  by 
exposing  a  mixture  of  carbon  monoxide  and  chlorine  gases 
to  sunlight,  and  was  used  for  "gassing"  in  the  great 
war,  being  a  suffocating  and  extremely  poisonous  gas. 
It  is  best  produced  by  passing  a  rapid  current  of  the  mixed 
gases,  at  the  ordinary  temperature,  over  highly  activated 
wood  charcoal,  the  product  being  liquefied  by  use  of  a 
freezing  mixture.  The  liquefied  carbonyl  chloride  has  a 
sp.  gr.  of  i -43  at  o°  C.,  boils  at  8-2°  C.  (so  that  it  immedi- 
ately assumes  the  gaseous  form  upon  exposure  to  the  air), 
and  crystallizes  at  -  128°  C.  Petrol,  benzol,  and  ethyl- 
acetate,  dissolve  an  equal  weight  of  the  gas,  and  these 
solutions  are  used  in  the  coal-tar  colour  industry  and  for 
exterminating  rats  and  moles. 

CARBONYLS— See  Metallic  Carbonyls. 

"  CARBORAFFIN  "—A  carbonaceous  decolorant  black,  made 
by  mixing  peat  with  a  strong  solution  of  zinc  chloride, 
drying,  and  heating  to  700°  F.,  the  zinc  being  subsequently 
washed  out  with  dilute  hydrochloric  acid  and  water. 


90  CARBORUNDUM— CARRAGHEEN 

CARBORUNDUM  (SiC)— A  greenish,  blue-black,  crystalline 
compound  of  carbon  and  silicon,  largely  used  by  reason  of 
its  great  hardness,  for  grinding  and  cutting  metals  in 
engineering  shops ;  made  by  heating  in  the  electric  furnace 
a  mixture  of  fine  sand  and  carbon  with  a  little  salt.  Its 
sp.  gr.  is  3-12  to  3-20. 

CARBOXYLIC  GROUP  (COO H)— Characteristic  of  the  mono- 
basic fatty  acids,  the  H  of  which  is  replaced  in  the 
formation  of  salts. 

CARBUNCLE— Garnet. 

CARDAMOMS — The  nearly  ripe  fruit  of  shrubs  (Elettaria  vepens, 
Alpinia  cavdamomum,  and  Amomum  repens)  which  grow  on 
islands  in  the  Indian  Sea,  and  are  used  as  condiments 
and  valuable  stimulant  aromatics.  They  yield  an  aro- 
matic essential  oil  amounting  to  from  3  to  8  per  cent., 
having  a  varying  sp.  gr.  of  from  0*895  t°  °'947 '»  rotation, 
+  22°  to  +46°;  and  refractive  index  of  1*460  to  1*4673, 
according  to  the  kind,  there  being  several  oils  on  the 
market,  known  as  Ceylon,  Malabar,  Siam,  etc.  Old  carda- 
mom oil  has  been  found  to  deposit  crystals  of  a  terpene 
hydrate  (C10H16,3H2O).  The  Ceylon  oil  is  said  to  contain 
chiefly  terpenes ;  the  Malabar  oil  contains  cineol  as  its 
chief  constituent;  while  the  Siam  oil  contains  borneol  as 
chief  constituent,  and  all  are  used  in  medicine  and  for 
flavouring  purposes. 

CARMINE — The  colouring  matter  of  cochineal,  prepared  by 
treating  the  watery  extract  of  cochineal  with  cream  of 
tartar,  alum,  or  acid  potassium  oxalate.  This  coagulates 
the  albuminous  constituents,  and  the  colouring  principle  is 
carried  down  with  the  precipitate.  It  is  soluble  in  water 
and  alcohol.  Carminic  acid,  the  active  principle,  would 
appear  to  have  the  formula  C22H24Oj2.  It  is  a  crystalline 
body  and  gives  well-defined  salts.  (See  also  Kermes.) 

CARNALLITE— See  Potassium. 
CARNAUBA  WAX  (Brazil  wax)— See  Waxes. 
CARNELIANS — A  species  of  chalcedony.     (See  Cornelians.) 

CARNOTITE — A  yellow  mineral  of  variable  composition  con- 
taining uranium  and  vanadium  with  lime  and  potash,  etc. 
It  is  radio-active,  and  a  source  of  radium. 

CARRAGHEEN  (Chondrus  crisfus] — See  Agar-Agar, 


CA  RRON  OIL-  CA  SSA  VA  9 1 

CARRON  OIL — A  mixture  of  olive  oil  and  lime-water  in  equal 
parts,  used  as  an  application  for  burns. 

CARROTENE— See  Chlorophyll. 

CARTHAMUS— See  Safflower. 

CARVENE — A  terpene  (C10H16)  contained  in  oil  of  cumin. 

CARVONE  (Carvol) — The  principal  constituent  of  oil  of  cara- 
way seeds  ;  a  liquid  ketonic  body  (C^H^O),  which  yields 
carvacrol  (a  liquid  substance  isomeric  with  thymol)  upon 
heating.  Its  sp.  gr.  is  0-9598,  and  boiling-point  224°  C. 

CASCARA  SAG-RADA — The  dried  bark  of  Rhamnus  purshianus, 
used  as  a  laxative. 

CASCARILLA  BARK  is   from  shrubs  (Croton  eleutheria  and 

Croton  cascavilld)  indigenous  in  the  West  Indies.  In  addition 
to  other  extractives,  it  yields  under  J  per  cent,  of  a  volatile 
aromatic  oil  and  a  crystalline  body  named  cascarillin.  The 
bark  infusion  is  used  medicinally  as  a  stomachic,  tonic,  and 
expectorant. 

CASEIN — The  nitrogenous  constituent  of  the  milk  of  mam- 
malia, forming  the  principal  constituent  of  cheese  in  which 
it  is  admixed  with  butter.  Chemically  it  is  to  be  regarded 
as  an  albuminous  body,  somewhat  allied  to  legumin  or 
vegetable  casein.  Associated  with  the  fat  of  the  milk,  it 
separates  when  the  milk  is  coagulated  either  by  heating 
with  or  without  the  addition  of  acetic  acid,  or  by  means  of 
rennet.  Its  composition  may  be  expressed  percentically  as 
follows : 

Carbon  53-8 

Hydrogen  ...         ...         ...         ...  j'2 

Nitrogen  ...         ...         ...         ...  15-6 

Oxygen  ...         ...          ...         ...  22^5 

Sulphur  ...          ...         ...         ...  0*9 


i  oo-o 


It  is  white  to  yellow  in  colour,  and  is  soluble  in  alkaline  solu- 
tions, but  not  in  water.  Industrially  it  is  prepared  by 
precipitation  with  sulphuric  acid  and  finds  large  employ- 
ment, considerable  quantities  being  also  imported,  particu- 
larly from  the  Argentine  Republic.  It  is  used  in  preparing 
adhesives,  ivory  substitutes,  paints,  etc. 

CASSAVA— A  starch  obtained  from  the  roots  of  the  manioc 
(Jatropha  manihot  L.)  which  grows  in  the  East  Indies,  and 
from  which  tapioca  also  is  prepared. 


92  CASSIA— CASTOR  OIL 

CASSIA  is  the  bark  of  the  Chinese  Cinnamomum  avomaticum. 
It  yields  from  |-  to  2  per  cent,  of  a  volatile  oil  by  distillation 
with  salt  water,  nearly  identical  with  cinnamon  oil,  and  is 
used  for  scenting  brown  Windsor  soap,  etc.  Cassia  buds 
from  the  Cinnamomum  lauresii  yield  the  same  oil  which, 
however,  is  not  so  aromatically  pleasant  as  cinnamon  oil. 
The  sp.  gr.  of  the  oil  is  1*05  to  1*065,  having  a  rotation  of 
+  i°  to  -  i°,  and  a  refractive  index  of  1*585  to  1*605. 

CASSITERITE— Another  name  for  tinstone.     (See  Tin.) 

CASTANHA  OIL  (Brazil-nut  oil)  is  expressed  from  Brazil 
nuts,  has  a  sp.  gr.  of  0-918,  a  saponifkation  value  of  193^5, 
and  iodine  value  106-22.  It  melts  at  0-4°  C.,  is  soluble  in 
ether  and  carbon  disulphide,  is  pale  yellow  in  colour,  and  is 
used  in  soap-making,  in  perfumery  and  as  a  food. 

CASTILE  SOAP  is  a  hard  soap  made  from  olive  oil,  and  is 
used  for  making  pills  and  plasters. 

CASTOR  OIL  is  a  thick,  non-drying,  yellowish  or  pale  green, 
odourless  oil,  extracted  or  expressed  from  the  seeds  of 
Riciuus  communis,  a  plant,  which  is  cultivated  in  the  East 
and  West  Indies,  Java,  Mexico,  and  other  warm  climates. 
It  is  a  mixture  of  several  glycerides,  and  upon  saponifica- 
tion  yields  a  soap  which  is  perfectly  dissolved  by  water.  Its 
chief  constituent  fatty  acid  is  ricinoleic  acid  (C18H34O3), 
which  melts  at  4°  to  5°  C.,  has  a  sp.  gr.  of  0-95,  and  re- 
sembles oleic  acid  in  properties.  The  seeds  of  the  plant 
yield  from  45  to  55  per  cent,  oil,  the  medicinal  oil  being 
prepared  from  seeds  which  have  been  husked,  while  the 
second  and  third  pressings  are  used  industrially. 

The  bleaching  of  castor  oil  is  usually  effected  by  agitation 
at  200°  F.  with  2  to  4  per  cent,  of  Fuller's  earth,  followed 
by  agitation  with  from  0-2  to  1-5  per  cent,  of  prepared 
decolorizing  carbon. 

In  addition  to  triricinolein,  it  also  contains  palmitic  and 
oleic  acids. 

The  pressed  cake  is  unfitted  for  cattle  food,  as  it  contains 
an  alkaloid  named  "  ricine,"  derived  from  the  husks  of  the 
seeds. 

Castor  oil  has  a  sp.  gr.  of  0-969,  a  saponification  value  of 
176  to  183,  an  iodine  value  of  83  to  86  ;  solidifies  at  -  18°  C., 
and  is  soluble  in  alcohol,  ether,  benzene,  etc. 

The  lower  qualities  are  used  for  soap-making  and  leather- 
dressing,  as  lubricants,  in  the  preparation  of  Turkey-red  oil, 
and  in  the  manufacture  of  artificial  leather,  linoleum,  and 
rubber  substitutes. 


CA  TA  LA  SE—CA  TALYTIC  93 

CATALASE — A  common  name  for  a  group  of  enzymes  (one 
of  which  can  be  prepared  from  germinated  beans),  which 
have  the  power  of  catalyzing  hydrogen  peroxide. 

CATALYTIC — The  term  given  to  a  remarkable  property  which 
is  exhibited  by  certain  substances  in  initiating  or  accelerating 
and  exhilarating  chemical  action  between  two  or  more  other 
chemical  substances.  For  example,  platinum  in  a  spongy 
condition  promotes  the  combination  of  hydrogen  and  oxygen 
gases  to  form  water ;  a  little  of  this  so-called  platinum  black, 
when  thrown  into  a  mixture  of  the  two  gases,  causes  them 
to  combine  with  a  loud  explosion.  It  also  causes  the 
ignition  of  coal  gas  in  presence  of  air,  and  there  is  an 
automatic  gas-lighter  constructed  on  this  principle. 

The  primary  alcohols  are  resolved  into  aldehydes  and 
hydrogen  by  passing  their  vapours  through  tubes  contain- 
ing certain  metals  or  their  oxides ;  for  example,  ethyl 
alcohol  gives  an  80  per  cent,  yield  when  passed  over  zinc 
at  660°  C.,  and  many  organic  compounds  can  be  reduced 
by  mixing  them  with  hydrogen  and  passage  over  platinum 
black  at  a  moderate  temperature.  Electrolytic  copper  does 
not  exercise  any  catalytic  effect  on  the  oxidation  of  ethyl 
alcohol,  but  when  prepared  by  reduction  of  the  oxide  it 
catalyzes  the  action  with  the  formation  of  acetaldehyde  or 
acetone. 

Fuming  sulphuric  acid  is  now  made  by  a  catalytic  pro- 
cess, and  the  catalytic  hydrogenation  of  oils  may  also  be 
cited  as  affording  another  illustration  of  catalytic  processes. 
(See  Hydrogenation.) 

Many  finely  divided  substances  are  capable  of  exercising 
a  catalytic  effect :  pure  precipitated  silica  after  moderate 
calcination  effects  the  decomposition  of  ethyl  alcohol  at 
280°  C.,  producing  ethylene.  Pulverized  quartz  and 
alumina  are  also  capable  of  serving  as  catalysts,  and  it  has 
been  shown  that  titanium  oxide  (TiO2)  at  a  temperature  of 
290°  to  300°  C.  effects  the  esterification  of  the  vapours  ot 
acids  and  alcohols.  In  addition  to  platinum  and  copper, 
iron,  nickel,  cobalt,  palladium,  osmium,  iridium,  ruthenium, 
and  rhodium  are  all  employed  as  catalysts,  and  for  the 
reduction  of  liquid  compounds.  The  catalyst  is  generally 
used  in  suspension,  being  removed  at  the  completion  of  the 
operation  by  filtration  or  otherwise.  There  are  substances 
which  act  as  anti-catalysts,  and  others  as  "  poisons  "  to  the 
catalysts,  and  of  course  it  is  important  that  these  should  be 
absent  in  all  such  operations. 

The  catalyst  is  often  unimpaired  at  the  end  of  the  action, 
although  its  action  is  probably  dependent  upon  the  forma- 


94  CATALYTIC— CELESTINE 

CATALYTIC  (Continued)— 

tion  of  intermediate  compounds.  In  some  cases  it  would 
appear  that  occlusion  or  adsorption  of  one  or  more  of  the 
interacting  substances  occurs  at  the  surface  of  the  catalyst, 
thus  securing  greater  concentration.  (See  also  Enzymes.) 

CATECHOL  (Pyrocatechin)  (C6H6O2  or  C6H4(OH)2)  is  a  so- 
called  dihydric  phenol,  contained  in  raw  beet  sugar  and 
the  leaves  of  the  Virginia  creeper,  and  obtainable  by  chemical 
processes  from  guaiacol  and  some  other  natural  resins.  It  is 
a  crystalline  body  which  melts  at  104°  C.,  is  readily  soluble 
in  water  and  alcohol,  and  can  be  sublimed.  It  is  antiseptic 
in  character,  and  used  in  photography. 

CATECHU  (Cutch)  — An  astringent  extract,  rich  in  tannin 
(25  to  50  per  cent.),  prepared  from  the  wood  and  pods  of 
various  species  of  acacia  and  other  catechu  plants,  grown 
in  Bombay,  Bengal,  Nubia,  and  elsewhere,  by  digest- 
ing the  various  parts  of  the  plants  in  water  and  evaporation 
of  the  solutions.  Apart  from  its  use  in  tanning,  it  is  used 
in  dyeing,  as  when  treated  with  nitric  acid  it  yields  a 
bright  yellow  powder  possessing  dyeing  characters  like 
those  of  picric  acid.  Catechu  contains  a  crystalline  principle 
named  catechin  (C15H14O64H2O)  readily  soluble  in  hot 
water  and  in  alcohol.  There  are  a  number  of  varieties 
including  gambia  catechu  (Catechu  pallidum)j  a  pale  sort ; 
betel-nut  catechu  ;  cutch  (Areca  catechu) ;  and  Nubian 
catechu  from  Egyptian  acacias. 

CATHARTIN — The  purgative  constituent  of  senna. 
CATHODE  RAYS— See  Radio-activity. 

CAT'S  EYE— A  quartz  of  translucent  appearance  found  in 
Ceylon. 

CAUSTIC  SODA— See  Sodium. 

CEDAR-WOOD  OIL  —  A  pale  yellow  essential  oil  of  agreeable 
odour,  used  in  perfumery  and  as  an  insectifuge,  obtained 
from  the  wood  of  thejuniperus  virginiana,  etc.,  to  the  extent 
of  about  1 6  ozs.  per  cwt.  Sp.  gr.  about  0-940  to  0-960; 
optical  rotation,  -25°  to  -38°;  refractive  index,  1*498 
to  1-504.  It  is  soluble  in  alcohol  and  ether,  and  contains 
a  crystalline  substance  named  cedar-camphor  (cedrene). 

CELERY  OIL — Distilled  from  the  fruit  of  Apium  graveolens, 
having  a  sp.  gr.  of  from  0-87  to  0*895.  ^  nas  *ne  odour  and 
taste  of  celery,  contains  limonene  associated  with  a  number 
of  other  substances,  and  is  used  for  flavouring  purposes. 

CELESTINE  (Celestite)— Native  strontium  sulphate  (SrSO4). 


CELL  U  LOW— CEMENT  95 

CELLULOID  (Xylonite) — In  the  preparation  of  this  material, 
cellulose  (usually  in  the  form  of  paper)  is  nitrated  with  a 
mixture  of  sulphuric  and  nitric  acids  until  the  nitrogen 
content  amounts  to  about  10  to  n  per  cent.,  and  after 
bleaching,  washing,  and  drying,  it  is  gelatinized  with  a 
mixture  of  camphor  dissolved  in  alcohol  into  a  jelly,  at 
which  stage  any  colouring  matters  may  be  introduced  as 
desired.  It  is  then  manipulated  on  hot  rollers,  and  pressed 
into  blocks  or  other  forms.  It  is  a  plastic  material  at  75°  C, 
and  after  evaporation  of  the  solvent  and  upon  cooling  can 
be  turned  on  a  lathe.  It  is  largely  used  for  making  combs, 
brush  and  knife  handles,  piano-keys,  billiard  balls,  collars, 
cycle  pumps,  mudguards,  etc.  The  celluloid  used  in  making 
cinematograph  films  is  of  a  more  highly  nitrated  character, 
while  the  proportion  of  camphor  incorporated  is  smaller, 
but  it  is  much  more  inflammable  in  character.  (See 
Explosives.) 

CELLULOSE  (C6H10O5)X — The  structural  and  preponderating 
tissue  forming  the  walls  or  skeletons  of  plants,  convertible 
into  sugar,  gun-cotton,  nitro-cellulose,  collodion,  artificial 
silk,  etc.,  and  extensively  employed  in  the  manufacture  of 
paper  and  compounding  celluloid  articles  and  the  prepara- 
tion of  celluloid  films,  some  of  which  have  a  basis  of  cellu- 
lose acetate  dissolved  in  acetone  or  cellulose  dissolved  in 
amyl  acetate  or  amyl  alcohol.  (See  Pyroxylin.) 

Cotton  contains  about  90  per  cent,  cellulose,  and  the  pro- 
portion in  woods  of  various  sorts  ranges  from  about  40  to 
60  per  cent.  (See  Paper.) 

Cellulose  is  soluble  in  an  ammoniacal  solution  of  cupric 
oxide,  and  this  solution  readily  dissolves  cotton  and  linen 
fibres.  Advantage  is  taken  of  this  solubility  in  the  manu- 
facture of  "  Willesden  paper." 

There  is  now  a  large  industry  also  in  the  manufacture  of 
artificial  silk  made  from  cellulose. 

Celluloses  used  for  industrial  purposes  are  of  three  classes 
— viz.,  the  so-called  pecto-celluloses  such  as  cotton,  ramie, 
flax,  and  hemp  ;  the  ligno-celluloses  such  as  jute  and  the 
various  woods  ;  and,  lastly,  cereal  straws  and  grasses. 

Ramie  and  hemp  contain  about  from  63  to  66  per  cent, 
cellulose.  (For  note  concerning  the  constitution  of  cellulose 
see  Glucose ;  see  also  Silk  Artificial,  and  Paper.) 

CEMENT  (Portland  cement)  is  prepared  from  a  mixture  of 
clay  and  chalk  (containing  about  76  per  cent,  of  the  latter), 
which  are  ground  together  in  water,  and  after  allowing  the 
mixture  to  settle,  the  water  is  poured  off  and  the  deposit  is 


96  CEMENT— CERIUM 

CEMENT  (Continued)— 

calcined  (intensely  heated).  It  is  then  ground  dry  ready 
for  use.  It  has  a  sp.  gr.  of  3*17,  and  on  the  average  it  con- 
tains about  22  per  cent,  silica  (SiO2),  62  per  cent,  lime 
(CaO),  and  7-5  per  cent,  alumina  (A12O3).  When  mixed 
with  a  small  proportion  of  water,  it  forms  a  very  hard  and 
tenacious  cement  which  expands  as  it  solidifies  or  "  sets," 
and — unlike  ordinary  mortar — can  be  used  for  hydraulic 
purposes.  Storage  of  cement  prolongs  the  time  of  initial 
and  final  setting. 

Cement  consists  mainly  of  lime  and  silica  combined  with 
a  certain  amount  of  alumina  and  small  amounts  of  potash, 
soda,  and  magnesia  in  the  form  of  free  salts. 

The  use  of  blast-furnace  slag  in  the  manufacture  of  cement 
is  now  largely  practised  in  the  North  of  England  and  Scot- 
land, where  suitable  clays  or  marls  are  rare. 

The  lime  which  is  set  free  during  the  setting  of  Portland 
cement,  like  the  slaked  lime  of  ordinary  mortar,  is  capable 
of  entering  into  combination  with  silica  when  presented  to 
it  in  a  sufficiently  active  form,  and  good  cement  can  there- 
fore be  improved  by  the  addition  of  a  suitable  pozzolanic 
substance.  (See  Concrete,  and  for  other  kinds  of  cement 
see  Sealing  Wax.) 

CENTRIFUGES  (Hydro-extractors) — Machines  for  extracting 
liquids  from  solids,  for  precipitating  fine  solids  from  liquids, 
and  for  separating  liquids  of  varying  specific  gravities  by 
-  centrifugal  action.  In  the  separation  of  liquids  from  solids 
by  rotation  of  the  mixture  in  a  cage  or  drum,  the  liquid  is 
expelled  through  openings  therein. 

CERAMIC— Pertaining  to  pottery. 

CERESINE— See  Waxes. 

CERITE — A  rare  mineral,  being  a  hydrated  silicate  of  cerium, 
containing  also  lanthanum  and  didymium,  from  which 
cerium  is  extracted. 

CERIUM  (Ce)  and  its  compounds — Atomic  weight,  140 ;  sp. 
gr.,  7 ;  melting-point  about  623°  C.  A  rare  element  found 
in  association  with  lanthanum  in  the  Swedish  minerals  cerite, 
allanite,  and  orthite,  also  in  gadolinite,  wohlerite,  and  monazite. 
It  resembles  iron  in  appearance,  oxidizes  quickly  in  moist 
air,  forms  alloys  with  iron,  aluminium,  zinc  and  magnesium, 
and  combines  with  boron  and  silicon.  It  is  malleable  and 
ductile. 

There  are  two  oxides,  Ce2O3  and  CeO2,  the  latter  of  which 
(ceria)  is  used  in  the  preparation  of  mantles  for  use  in 
incandescent  gas  lighting. 


CER1  UM—CHEDDIT&  9? 

CERIUM  (Continued)— 

The  oxalate  (Ce2(C2O4)39H2O)  and  the  insoluble  fluoride 
(CeF4.H2O)  (by-products  in  the  manufacture  of  thorium 
from  monazite  sand)  were  both  used  during  the  war  in 
connection  with  searchlights  and  tracer  bullets.  The 
oxalate  is  but  slightly  soluble  in  water,  and  in  addition  to 
its  other  uses  is  employed  medicinally  for  the  prevention 
of  chronic  vomiting.  (See  also  Pyrophoric  Alloys.) 

CEROTIC  ACID  (C26H52O2)— A  crystalline  fatty  acid  of  the 
normal  series  and  the  chief  constituent  of  beeswax,  being 
contained  in  combination  as  cerylic  cerotate  (C25H51.CO. 
OC26H5?)  in  Chinese  wax.  It  melts  at  78°  C.  and  is 
soluble  in  hot  alcohol.  It  can  be  obtained  from  Chinese 
wax  by  melting  that  substance  with  potash  or  by  its  dry 
distillation,  and  from  paraffin  wax  by  oxidation  with 
chromic  acid. 

CEROTIN— Chinese  wax. 

CERUSSITE  (White-lead  ore) — A  mineral  lead  carbonate 
(PbCO3)  of  importance  as  an  ore  of  lead,  found  in  Corn- 
wall, Cumberland,  Scotland,  Mexico,  and  some  of  the 
United  States. 

CETIN — The  wax-like  constituent  of  spermaceti.    (See  Waxes.) 

CHALCANTHITE  — Native  copper  sulphate  (CuSO4,5H2O) 
found  in  some  Chilian  mines,  Arizona,  and  elsewhere. 

CHALCEDONY — A  variety  of  quartz.  (See  Silicon  and 
Cornelians.) 

CHALCOCITE  (Copper  glance) — A  natural  copper  sulphide. 

CHALK — Native  calcium  carbonate  of  an  earthy  character, 
used  to  some  extent  as  a  dressing  for  heavy  lands,  also  for 
building  purposes  and  in  making  cement. 

CHALYBEATE  WATERS — These  include  those  found  and 
used  as  medicines  at  Tunbridge  Wells,  Cheltenham, 
Harrogate,  Leamington,  Scarborough,  Strathpeffer,  and 
elsewhere.  They  contain  iron  as  ferrous  carbonate  in  a  state 
of  solution  and  constitute  valuable  tonics  in  cases  of  debility. 

CHARCOAL— See  Carbon. 

CHAULMOOGRA  OIL— A  thick,  yellowish  oil  or  soft  fat,  of 
acrid  taste,  expressed  from  the  seeds  of  Taraktogenos  Kurzii; 
of  sp.  gr.  0-94  and  iodine  value  96  to  104.  Used  in  medicine. 
It  is  soluble  in  alcohol,  ether,  etc.  The  seeds,  which  are 
imported  from  India,  yield  about  33  per  cent,  of  the  oil. 

CHEDDITE — See  Explosives, 

7 


98  CHEESE— CHEMICAL  CHANGES 

CHEESE  is  made  from  milk  by  coagulation  with  rennet  and 
represents  its  casein  constituent  with  some  of  its  butter. 
It  undergoes  certain  chemical  changes  upon  keeping,  which 
are  not  well  understood,  and  is  a  valuable  food  containing 
a  considerable  amount  of  nitrogen.  It  varies  in  composition 
according  to  the  milk  from  which  it  is  made  and  to  details 
in  the  process  of  manufacture.  It  contains  from  30  to  60 
per  cent,  water,  2|  to  5^  per  cent,  nitrogen,  from  19  to 
33  per  cent,  fat,  and  from  4^  to  7  per  cent,  mineral  sub- 
stances (ash).  Roquefort  cheese  is  made  from  a  mixture  of 
sheep's  and  goat's  milk,  and  Gruyere  cheese  was  originally 
made  exclusively  from  goat's  milk,  but  is  now  made  from 
cow's  milk. 

CHEMICAL  ATTRACTION  or  affinity  (the  force  or  power  which 
brings  about  chemical  combination  and  keeps  the  resulting 
compounds  comparatively  intact  as  entities)  is  correlated  to 
other  forms  of  force,  such  as  heat,  light,  electricity,  mag- 
netism, and  gravitation,  and  all  chemical  changes  involve 
the  consumption  or  expenditure  of  energy  to  bring  them 
about,  many  being  attended  with  the  production  of  heat, 
light  or  electricity. 

CHEMICAL  CHANGES— All  articles  of  food  and  clothing,  the 
materials  of  which  our  houses  and  buildings  are  constructed 
and  which  are  needed  for  their  decoration  or  repair,  every 
art  and  every  industry — all  depend  essentially  for  their 
production  or  activity  upon  chemical  changes  as  realized  in 
nature  or  made  by  man  to  serve  human  purposes.  The 
same  is  true  of  the  production  and  decay  of  animal  and 
vegetable  matters,  as  also  the  processes  by  which  they  are 
broken  up  and  the  resulting  products  made  available  in 
their  turn  as  food  for  new  life :  the  very  diseases  of  man- 
kind and  animals,  as  also  their  treatment,  are  all  chemical  in 
essence  and  involve  chemical  changes.  These  chemical 
changes  constitute  a  sort  of  adaptation  of  matter  to  environ- 
ment, and  in  a  sense  are  acts  of  creation,  as  every  such 
change  produces  products  which,  although  related,  are 
quite  distinct  in  character  and  properties  from  the  original 
substances  which  give  rise  to  them  when  subjected  to  the 
required  influences.  Thus,  in  a  very  literal  sense,  all  matter 
— which,  as  will  be  seen  in  other  places,  appears  to  be  essen- 
tially one  in  nature — is  actuated  by  a  spirit  of  life,  being 
susceptible  to  change  when  the  environment  is  appro- 
priate. In  other  words,  the  liability  to  change  is  equivalent 
to  life.  All  such  changes  are  necessarily  accompanied  by 
a  relationed  redistribution  of  energy.  (See  Atoms,  Ele- 
ments, and  Radio-activity.) 


CHEMICAL  COMPOUNDS  99 

CHEMICAL    COMPOUNDS— There    is  a  fundamental  differ- 
ence between  a  mere  mixture  and  a  chemical  compound. 

If  some  lead  shots  be  mixed  with  some  powdered  sulphur 
ever  so  carefully,  they  can  be  easily  separated  again.  For 
instance,  the  sulphur  can  be  blown  away  from  the  mixture 
by  the  use  of  a  bellows,  or  all  the  shots  can  be  picked  out 
and  removed  one  by  one.  But  if,  instead  of  removing  the 
shots,  the  mixture  is  subjected  to  strong  heat,  both  the 
lead  and  the  sulphur  disappear  as  such.  They  enter  into 
combination  with  each  other  in  a  chemical  sense,  and  a 
new  substance  or  chemical  compound  is  formed,  named 
lead  sulphide,  which  has  properties  or  qualities  quite 
different  from  those  of  its  constituents.  The  tarnish  which 
forms  on  articles  of  silver  when  exposed  to  the  air  of 
towns  is  also  a  chemical  combination  of  silver  and  sulphur 
(silver  sulphide)  due  to  the  presence  of  traces  of  a  compound 
of  sulphur  in  the  air. 

Iron  filings  may  be  mixed  ever  so  carefully  with  sand ; 
but  this,  again,  is  a  mere  mixture,  and  all  the  iron  filings 
may  be  separated  or  withdrawn  from  the  mixture  by 
means  of  a  magnet,  which  attracts  the  iron  and  not  the 
sand,  showing  that  they  are  not  in  chemical  combination, 
but  only  mechanically  admixed. 

Gunpowder  is  only  a  mechanical  admixture  of  nitre, 
charcoal,  and  sulphur,  and  their  separate  respective 
particles  can  be  seen  lying  apart  from  each  other  by  means 
of  the  microscope. 

As  a  further  instance  of  the  difference  between  a  mere 
mixture  and  a  chemical  compound  it  may  be  mentioned 
that  when  quicksilver  (mercury)  is  heated  and  exposed  to 
the  air,  it  becomes  changed  into  a  yellow  powder  (an  oxide 
of  mercury),  which  is  a  chemical  compound  of  the  mercury 
and  atmospheric  oxygen,  and  by  no  mere  mechanical 
process  can  the  mercury  and  the  oxygen  of  which  it  is 
compounded  be  separated  from  each  other,  showing  that 
it  is  not  a  mere  mixture  of  the  two  things. 

Chemical  combination  always  takes  place  in  equivalent 
weights,  or  so-called  combining  proportions  of  the  elements 
concerned,  and  the  combining  weights  are  the  smallest 
which  will  combine  with  one  part  of  hydrogen. 

Lead,  for  example,  has  an  atomic  weight  of  207,  so  that 
when  it  enters  into  chemical  combination  with  sulphur, 
which  has  an  atomic  weight  of  32,  207  parts  by  weight  of 
lead  combine  with  32  parts  by  weight  of  sulphur,  and  yield 
239  parts  of  the  chemical  compound  sulphide  of  lead. 

Salt   (sodium   chloride)    is   a   chemical   combination   of 


ioo  CHEMICAL  COMPOUNDS 

CHEMICAL  COMPOUNDS  (Continued)— 

23  parts  by  weight  of  the  metal  sodium  and  35^  parts  by 
weight  of  the  gas  chlorine,  or,  in  other  words,  a  combina- 
tion of  one  atom  of  each  of  these  two  elements.  The  two 
atoms  thus  combined  make  up  a  molecule,  so  that  the 
molecular  weight  of  the  compound  (salt)  is  that  of  the  two 
added  together  —  namely,  58^.  When  salt  is  decomposed  — 
that  is,  split  up  by  chemical  means  into  its  two  constituent 
elements  —  58^  parts  by  weight  always  yield  23  parts  by 
weight  of  sodium  and  35  J  parts  by  weight  of  chlorine. 

Most  of  the  oxides,  hydrates  and  carbonates  of  the  metals 
behave  as  bases,  and  in  common  with  the  alkalies  combine 
with  acids  to  form  salts. 

When  an  acid  solution  is  mixed  with  its  equivalent 
quantity  of  an  alkaline  or  other  basic  solution,  the  acid 
character  of  the  one  solution,  and  the  alkaline  or  basic 
character  of  the  other  solution,  are  severally  destroyed  or 
neutralized. 

For  example,  if  a  solution  of  sodium  hydrate  in  water  be 
mixed  with  one  of  hydrochloric  acid,  a  chemical  interaction 
takes  place,  and  a  salt  known  as  sodium  chloride  (common 
salt)  is  produced  in  solution.  This  is  represented  by 
formula  or  equation  as  follows  : 

NaHO  +  HCl=NaCl  +  H20, 

and  if  the  neutral  solution  which  results  from  this  reaction 
be  heated  so  as  to  cause  evaporation  of  sufficient  of  the 
water,  the  salt  will  be  obtained  upon  cooling  of  the  solu- 
tion, in  a  crystalline  condition. 

Lime  (calcium  oxide,  CaO)  is  an  example  of  another 
class  of  bases,  which  includes  baryta  or  barium  oxide 
(BaO),  magnesia  or  magnesium  oxide  (MgO),  and  strontia 
or  strontium  oxide  (SrO).  When  lime  is  added  to  hydro- 
chloric, nitric,  or  sulphuric  acid,  it  enters  into  combination 
and  forms  either  calcium  chloride,  nitrate,  or  sulphate,  as 
the  case  may  be.  Thus,  if  hydrochloric  acid  be  employed, 
the  change  is  expressed  as  follows  : 

CaO  +  2HC1  =  CaCl2  +  H2O, 
with  nitric  acid  as  follows  : 


and  with  sulphuric  acid  as  follows  : 

CaO  +  H2S04  =  CaS04  +  H2O. 


CHEMICAL  Cf)MPpUN&ff>*'.  --,  :-         .  101 

CHEMICAL  COMPOUNDS  (Continued)— 

The  chloride  and  nitrate  of  calcium  are  both  soluble  in 
water,  but  the  sulphate  is  almost  insoluble. 

Oxides,  Chlorides,  Bromides,  Iodides,  and  Other  Compounds. 
—It  has  already  been  stated  that  combinations  or  compounds 
of  metals  and  other  bases  with  oxygen  are  called  oxides,  and 
as  further  instances,  mention  may  be  made  of  the  oxides 
of  zinc,  lead,  and  copper,  which  are  represented  by  the 
chemical  formulae  ZnO,  PbO,  and  CuO  respectively. 

If  in  place  of  oxygen  the  elements  chlorine,  bromine, 
iodine,  fluorine,  and  sulphur  be  severally  taken  and  made 
to  combine  with  metals  or  other  bases,  the  resulting 
compounds  are  chlorides,  bromides,  iodides,  fluorides,  and 
sulphides. 

This  is  shown  in  tabulated  form  as  below : 


Compounds  of  — 

Called- 

Example. 

Formula. 

Oxygen 

Oxides 

Zinc  oxide 

ZnO 

Chlorine 

Chlorides 

Sodium  chloride 

NaCl 

Bromine 

Bromides 

Potassium  bromide 

KBr 

Iodine 

Iodides 

Potassium  iodide 

KI 

Fluorine 

Fluorides 

Calcium 

CaF2 

Sulphur 

Sulphides 

Lead  sulphide 

PbS 

The  names  used  to  identify  chemical  substances  are 
designed  as  far  as  possible  to  indicate  their  composition, 
but  the  system  is  by  no  means  perfect,  and  apart  from 
other  variations,  many  old  common  or  familiar  names  are 
still  retained  and  used  in  many  books. 

It  frequently  happens  that  the  same  two  chemical  ele- 
ments combine  together  in  various  proportions,  so  forming 
as  many  different  compounds,  and  to  distinguish  these, 
terminal  letters  or  prefixes  are  employed.  For  instance, 
the  two  compounds  water  and  hydrogen  dioxide  (H2O  and 
H2O2  respectively)  are  both  composed  of  hydrogen  and 
water,  so  the  one  with  the  higher  proportion  of  oxygen  is 
styled  dioxide  or  peroxide,  water  being  oxide  or  hydrogen 
monoxide. 

Again,  phosphorus  combines  with  chlorine  to  form  two 
chlorides,  PC13  and  PC15,  and  these  are  termed  respectively 
phosphorous  chloride  and  phosphonc  chloride,  or  prefer- 
ably, phosphorus  tfn'chloride  and  phosphorus  pentachloride 
respectively. 


102  a  •Q&EMFCAL  COMPOUNDS 

CHEMICAL  COMPOUNDS  (Continued)— 

Acids  are  eommonly  called  by  their  familiar  names,  but 
may  be,  and  often  are,  described  as  compounds  of  hydrogen 
— for  instance : 

Hydrochloric  acid     =    Hydrogen  chloride. 
Nitric  acid  =    Hydrogen  nitrate. 

Sulphuric  acid  =    Hydrogen  sulphate. 

The  terminals  ic  and  ous  are  used  to  denote  acids  with 
the  greater  or  smaller  proportion  of  oxygen,  where  that 
element  enters  into  their  combinations ;  thus  we  get : 

Sulphuric  acid,  formed  from  sulphur  tfn'oxide  and  water, 
S03+H20  =  H2S04. 

Sulphurous  acid,  formed  from  sulphur  ^'oxide  and  water, 
S02  +  H2O=H2S03. 

Nitn'c  acid,  formed  from  nitrogen  pentoxide  and  water, 
N205  +  H20=2HN03. 

Nitnws  acid,  formed  from  nitrogen  trioxide  and  water, 
N203  +  H2O=2HN02. 

When  these  acids  combine  with  bases  —  for  example, 
potassium  oxide — they  form  respectively  sulphate,  sulphate, 
nitrate,  and  nitrate  of  potassium  ;  or,  instead  of  expressing 
them  as  named,  they  may  be  described  as  potassium  sul- 
phate, sulphite,  nitrate  and  nitrite  respectively. 

The  table  on  p.  103  shows  which  of  the  various  compounds 
of  the  better-known  elements  are  soluble  or  insoluble  in 
water.  It  will  be  observed  that  some  metals,  including 
copper,  iron,  mercury,  and  tin,  form  two  compounds  of 
most  of  the  classes,  and  these  are  indicated  by  the  termina- 
tions of  the  metallic  names  :  thus,  ferric  chloride  is  FeCl3, 
and  ferrows  chloride  is  FeCl2 ;  mercurii  chloride  is  HgCl2 ; 
and  mercurows  chloride  is  Hg2Cl2,  and  so  forth.  It  will  be 
seen  that  the  names  of  the  compounds  containing  the 
larger  proportion  of  metal  end  with  the  termination  ous  ; 
and  those  with  the  smaller  proportion,  with  the  ending  ic. 

Carbonates  —  These  compounds  are  described  under 
Carbon. 

Carbides  are  combinations  of  carbon  with  metals,  such 
as  calcium  carbide  and  a  form  of  cast-iron,  and  these  are 
severally  referred  to  elsewhere. 

Nitrides  are  combinations  of  nitrogen  with  metals,  and 
are  formed  by  passing  ammonia  gas  over  the  metals  heated 


CHEMICAL  COMPOUNDS 


103 


CHEMICAL  COMPOUNDS  (Continued)— 

in  porcelain  tubes  to  from  400°  to  800°  C.,  the  ammonia 
being  thus  decomposed  into  its  constituent  elements. 

Hydrides  are  combinations  of  hydrogen  with  metals — as, 
for  example,  arsenic  hydride  (AsH3). 

Phosphides  are  compounds  of  phosphorus  with  metals. 
(See  Phosphorus.) 


1 

•j 

CO 

CO 

1 

1 

<5 

"rt 

rf 
r* 

T3 

fl 

"ri 

^2 

•§ 

s 

1 

1 

1 

jl 

id 

o 

E 

5 

0 

U 

52 

"3 

C/) 

5 

Al  .  . 

I 

I 



s 

s 

s 

I 

NH4 

s 

s 

s 

s 

s 

s 

s 

Sb 

I 

I 



s 



I 

I 

As  .  . 

ss 

s 



s 

— 

— 

I 

Ba  .  . 

s 

s 

I 

s 

s 

I 

I 

Ca  .  . 

ss 

ss 

I 

s 

s 

ss 

ss 

rnfCupric 
/u\Cuprous 

I 
I 

I 

I 
I 

s 

I 

s 

s 

I 
I 

Fef  Ferric 
re\Ferrous 

I 
I 

I 
I 

I 

s 
s 

s 
ss 

s 
s 

I 

I 

Pb.. 

I 

ss 

I 

ss 

s 

I 

I 

Mg 

I 

I 

I 

s 

s 

s 

s 

Mn 

I 

I 

I 

s 

s 

s 

I 

TT  /Mercuric 
g\Mercurous 

I 
I 

I 
I 

I 
I 

s 
I 

s 
s 

s 
s 

I 
I 

K    .. 

s 

s 

s 

s 

s 

s 

s 

Ag  .  . 

I 

I 

I 

I 

s 

ss 

I 

Na  .  . 

s 

s 

s 

s 

s 

s 

s 

«f  Stannic 
su\Stannous 

I 
I 

I 
I 

I 

I 

s 

s 

s 
s 

s 
s 

I 
I 

Sr    .. 

ss 

s 

I 

s 

s 

I 

ss 

Zn  .  . 

I 

I 

I 

s 

s 

s 

I 

S^  soluble,  SS  =  sparingly  soluble,  I  =  insoluble  in  water. 

Silicon,  Boron,  and  Selenium,  in  combination  with  metals 
form  silicides,  borides,  and  selenides,  and  so  far  as  these 
substances  are  of  importance,  they  find  description  under 
other  headings. 

Anhydrides  as  a  class  are  related  to  the  acid-forming 
oxides,  such  as  sulphur  trioxide  (SO3),  which  by  combina- 
tion with  water  gives  sulphuric  acid  (H2SO4) — that  is, 


104          CHEMICAL  COMPOUNDS— INTERACTIONS 

CHEMICAL  COMPOUNDS  (Continued)— 

By  abstracting  or  taking  away  the  water  from  sulphuric 
acid  it  is  reduced  to  its  anhydride.  The  term,  however,  is 
used  more  generally.  (See  Anhydrides.) 

Cyanides — See  Cyanogen. 

Arsines,  Phosphines,  and  Stibines — Three  series  of  very 
oxidizable  compounds  formed  by  replacing  hydrogen  of 
arsenic  hydride  (As2H3),  hydrogen  phosphide  (PH3),  and 
antimony  hydride  (SbH3)  by  hydrocarbon  groups. 

Hydrosulphides — See  Sulphur. 
CHEMICAL  CONSTANTS— See  Constants. 
CHEMICAL  ELEMENTS— See  Elements. 
CHEMICAL  EQUATIONS— See  Chemical  Interactions. 

CHEMICAL  FORMULAE— See  Chemical  Compounds,  Ele- 
ments, and  Formulae. 

CHEMICAL  INTERACTIONS  (Reactions  and  Equations)— If 
some  zinc  filings  be  placed  in  a  dilute  solution  of  hydro- 
chloric acid,  a  chemical  change  or  interaction  is  seen  to  take 
place,  the  metal  being  gradually  dissolved,  attended  with 
an  effervescence  due  to  the  formation  of  hydrogen  gas, 
whilst  a  solution  of  zinc  chloride  is  produced  as  the  result 
of  the  change. 

Using  symbols,  this  chemical  change  is  represented  as 
follows  : 

Zn  (zinc)  +  2HCl  (hydrochloric  acid) 
=  ZnCl2  (zinc  chloride)  -f  H2 ; 

that  is  to  say,  i  atom  of  zinc  and  2  molecules  of  hydro- 
chloric acid  give  rise  by  interaction  to  i  molecule  of  zinc 
chloride  (which  passes  into  solution)  and  2  atoms  of  hydro- 
gen gas. 

Similarly,  if  some  broken  pieces  of  marble  (which  con- 
sists of  calcium  carbonate)  be  placed  in  a  dilute  solution  of 
hydrochloric  acid,  they  dissolve  therein,  with  effervescence, 
due  to  the  escape  of  carbon  dioxide  gas,  which  results,  in 
consequence  of  the  chemical  change  that  takes  place 
between  the  marble  and  the  acid.  This  change  is  expressed 
as  follows : 

CaCO3  (calcium  carbonate,  or  marble) +  2HC1  (hydro- 
chloric acid)  =  CaC!2  (calcium  chloride)  +  H2O  (water)  + 
CO2  (carbon  dioxide).  In  other  words,  i  molecule  of 
calcium  carbonate  and  2  molecules  of  hydrochloric  acid 
produce  i  molecule  of  calcium  chloride  (which  passes  into 


CHEMICAL  INTERACTIONS  105 

CHEMICAL  INTERACTIONS  (Continued)  — 

solution),  i  molecule  of  water,  and  i  molecule  of  carbon 
dioxide. 

The  elemental  substance  called  phosphorus  (which,  in 
one  of  its  forms,  is  extensively  used  in  making  the  com- 
position used  for  coating  the  surface  of  match-boxes)  has  a 
great  affinity  for — that  is,  a  liking  or  tendency  to  enter  into 
chemical  combination  with — oxygen,  which  is  one  of  the 
constituents  of  the  air,  and  if  a  piece  of  phosphorus  be 
sufficiently  warmed  (heated  to  34°  C.)  or  ignited,  and  then 
placed  in  a  glass  jar  filled  with  oxygen  gas,  it  combines 
with  it  at  once,  bursts  into  vivid  flame,  and  after  cooling, 
it  is  found  that  on  the  bottom  and  sides  of  the  glass  jar 
there  is  a  white  deposit  resembling  snow. 

This  deposit  is  the  product  or  result  of  the  chemical 
action,  being  what  is  called  an  oxide  of  phosphorus 
having  the  formula  P2O5.  In  this  chemical  change  2  atoms 
of  phosphorus  weighing  twice  31  =  62  (31  being  the  atomic 
weight  of  P)  combine  with  5  atoms  of  oxygen,  weighing  in 
all  80  (i 6  being  the  atomic  weight  of  oxygen),  and  make 
142  parts  by  weight  of  the  resulting  product.  Now,  as  air 
consists  of  a  mixture  of  oxygen  and  nitrogen,  if  enough 
phosphorus  be  employed  to  use  up  all  the  oxygen  that  is 
present,  only  nitrogen  is  left  behind  in  the  gaseous  state. 
Supposing  exactly  100  parts  of  air  be  used  in  this  experi- 
ment, 21  parts  of  the  air,  consisting  of  oxygen,  enter  into 
chemical  combination  with  the  phosphorus,  and  79  parts  of 
the  air,  consisting  of  nitrogen,  are  left  behind. 

Heat  is  often  given  out  as  the  result  of  chemical  inter- 
changes, but  not  always  ;  sometimes  the  reverse  is  ex- 
perienced, and  cold  is,  so  to  speak,  produced. 

When  charcoal  or  coke — consisting,  in  the  main,  of  the 
element  carbon — is  burned  in  an  ordinary  fire-grate,  the 
carbon  enters  into  chemical  combination  with  the  oxygen 
present  in  the  air,  and  produces  carbon  dioxide.  This  is 
represented  by  symbols  in  the  following  equation  : 

C+02  =  C02. 

Each  atom  of  carbon  chemically  combines  with  2  atoms 
of  oxygen,  and  gives  rise  to  the  formation  of  i  molecule 
of  carbon  dioxide  gas. 

It  is  to  be  noted  that  in  this  interaction  a  solid  body 
combines  with  a  gas,  whilst  the  product  is  entirely  gaseous 
in  character,  although  it  can,  in  point  of  fact,  be  converted 
into  the  liquid  state  and  even  made  into  a  solid  form  like 
snow  by  great  cooling  under  pressure — that  is  to  say,  by 


106  CHEMICAL  INTERACTIONS 

CHEMICAL  INTERACTIONS  (Continued)— 

squeezing  (pumping)  a  great  quantity  (volume)  of  the 
carbon  dioxide  gas  into  a  very  small  space  whilst  cooling 
or  freezing  it  at  the  same  time. 

Mercuric  chloride  is  a  combination  of  mercury  with 
chlorine,  and  if  a  strip  of  copper  be  placed  in  a  slightly 
acid  solution  of  that  substance,  a  change  takes  place, 
causing  the  mercury  to  be  deposited,  whilst  after  sufficient 
time,  nothing  but  chloride  of  copper  is  found  in  solution. 
In  other  words,  the  mercury  is  replaced  (in  consequence  of 
the  chemical  change  that  takes  place)  by  the  copper,  and 
it  is  found  in  practice  that  this  exchange  takes  place  in 
the  proportion  of  200-6  parts  of  mercury  and  63-5  parts  of 
copper.  If  this  solution  of  chloride  of  copper  be  taken 
afterwards  and  exposed,  in  turn,  to  the  action  of  a  piece  of 
iron,  the  whole  of  the  copper  can  be  deposited  from  the 
solution  and  replaced  by  iron  ;  and  now  it  is  found  that 
the  metals  are  again  exchanged  in  their  equivalent  or 
atomic  weights,  63-5  parts  copper  being  replaced  by  56  parts 
iron.  These  two  changes  or  interactions  are  expressed  by 
the  two  following  chemical  equations : 

HgClg  (mercuric  chloride)  +  Cu   (copper)  =  CuCl2   (cupric 
chloride)  +  Hg  (mercury). 

CuCl2  (cupric  chloride)  +  Fe  (iron)  =  FeCl2  (ferrous  chloride) 
+  Cu  (copper). 

Baryta  or  barium  oxide  is  represented  by  the  formula 
BaO,  but  there  is  another  oxide  of  barium,  which  chemists 
call  barium  dioxide,  which  has  the  formula  BaO9. 

Similarly,  water,  which  is  an  oxide  of  hydrogen,  has 
the  formula  H2O,  but  there  is  another  oxide  of  hydrogen 
which  chemists  term  hydrogen  dioxide  or  peroxide  of 
hydrogen  (H2O2). 

Now,  when  powdered  barium  dioxide  is  added  to  a 
solution  of  dilute  hydrochloric  acid  (which  has  the  constitu- 
tion represented  by  the  formula  HC1),  the  following  change 
takes  place : 

Ba02  +  2HC1  =  BaCl2  +  H2O2. 

This  chemical  equation  represents  the  fact  that  i  mole- 
cule of  barium  dioxide  interacting  with  2  molecules  of 
hydrochloric  acid  (hydrogen  chloride)  produces  i  molecule 
of  barium  chloride  and  i  molecule  of  hydrogen  dioxide, 
both  of  which,  being  soluble  in  water,  remain  together  in 
solution. 


CHEMICAL  INTERACTIONS-CHESSYLITE  107 

CHEMICAL  INTERACTIONS  (Continued)— 

It  is  further  evident  that  the  sum  of  the  products  is  equal 
to  the  sum  of  the  substances  originally  employed,  and  the 
equation  given  above  shows  that  there  are  employed  in 
this  chemical  interaction  : 

1  atom  or  137  parts  by  weight  of  barium     \As  contained  in  i  molecule 

2  atoms  or    32     ,,  ,,      of  oxygen     /     of  barium  dioxide. 

2      ,,      ,,       2     ,,  ,,      of  hydrogen \  As  contained  in  2  molecules 

2      ,,      ,,     71     ,,  ,,      of  chlorine  /     of  hydrochloric  acid, 

totalling  7  atoms  and  242  parts  by  weight ; 
and  that  there  are  produced — 

1  atom  or  137  parts  by  weight  of  barium      \As  contained  in  i  molecule 

2  atoms  or  71     ,,  „       of  chlorine    /     of  barium  chloride. 

2      ,,       ,,      2     ,,  ,,       of  hydrogen  }  As  contained  in  i  molecule 

2      ,,       ,,   32     ,,  ,,       of  oxygen      J      of  hydrogen  dioxide, 

totalling  7  atoms  and  242  parts  by  weight. 

Incidentally,  this  equation  also  affords  an  illustration 
of  the  indestructibility  of  matter,  the  forms  and  combina- 
tions of  which  only  can  be  changed. 

If  in  the  study  of  any  chemical  change,  the  sum  of  the 
products  found  upon  analysis  is  not  equal  to  the  parts  by 
weight  of  the  substances  employed,  it  is  known  to  the 
operator  that  the  analysis  is  imperfect. 

CHEMICAL  PLANT  means  the  manufacturing  apparatus  re- 
quired in  respect  of  the  production  of  chemicals  on  a  large 
scale,  and  involves  the  application  of  engineering  drawings 
and  construction,  based  upon  a  knowledge  of  the  properties 
of  the  materials  to  be  employed — questions  of  heat-absorp- 
tion and  evolution,  its  transfer  and  transmission,  and 
other  fundamental  principles,  including  calculations  as  to 
the  quantities  and  capacities  to  be  dealt  with  by  the  various 
sections ;  in  other  words,  the  magnification  of  those  con- 
ditions ascertained  in  laboratory  practice  to  realize  the 
best  results  attainable,  having  particular  regard  to  the  use 
of  materials  capable  of  resisting  those  forms  of  chemical 
attack  which  may  be  anticipated. 

CHEMICAL  SYMBOLS — See  Elements,  Chemical  Compounds, 
Chemical  Interactions,  and  Formulae. 

CHEMISTRY  (Definition) — The  study  of  the  laws  of  changes  of 

matter. 
CHENOPODIUM  OIL — Distilled  from  the  fruit  of  Chenopodium 

ambrosioides  and  used   as   an   anthelmintic,   containing   an 

active  principle  named  ascaridole.   Sp.  gr.,  about  0-96  to  0-98. 
CHESS YLITE — Native  blue  oxycarbonate  of  copper  (2CuCO3, 

Cu(OH)2)  found  at  Chessy  near  Lyons, 


io8  CHIA   OIL—CHLORANILINES 

CHI  A  OIL— Expressed  from  the  seeds  of  the  Chia  plant  (Salvia 
hispanica),  which  grows  in  Mexico,  and  yields  from  24  to 
33  per  cent.,  having  a  sp.  gr.  0-9338,  iodine  value  196-3,  and 
saponification  number  192-2.  It  dries  as  quickly  as  linseed 
oil,  is  of  clear  yellow  colour,  with  odour  and  taste  like 
those  of  linseed  oil,  and  is  said  to  be  largely  used  as  a  food 
and  in  compounding  a  particular  drink. 

CHICORY — The  root  of  the  Chicorium  intybus  roasted  and 
ground  and  used  to  mix  with  coffee.  A  strong  infusion  is 
said  to  act  as  an  aperient  and  sometimes  as  a  diuretic. 

CHILI  NITRE— See  Caliche. 

CHILI  SALTPETRE— See  Caliche. 

CHINA  (Porcelain,  Pottery,  Stoneware,  etc.) — Articles  made 
from  various  classes  of  minerals,  such  as  China  clay,  a 
product  resulting  from  the  gradual  decomposition  of  rocks 
(including  felspar  and  granite)  in  the  nature  of  hydrous 
aluminium  silicates.  (See  Clay  and  Porcelain.) 

CHINESE  BLUE— A  form  of  Prussian  blue. 
CHINESE  INK— See  Inks. 
CHINESE  WAX— See  Waxes. 
CHINESE  WOOD  OIL-See  Tung  Oil. 

CHLORACETIC  ACID  (CH2C1,CO2H)— A  deliquescent  crys- 
talline halogen  substitution  product  of  acetic  acid,  used  as  a 
corn  and  wart  remover,  and  in  the  synthetic  production  of 
indigo. 

CHLORAL  HYDRATE  (C2H3C13O2)— A  crystalline  substance 
which  melts  at  57°  C.,  is  readily  soluble  in  water  and 
alcohol ;  used  as  a  soporific,  and  having  antiseptic  proper- 
ties. By  the  action  of  sulphuric  acid  it  is  converted  into 
chloral  (CC13.CHO),  a  thin  oily  liquid  of  sp.  gr.  1-5 12, 
which  boils  at  98°  C.,  and  becomes  reconverted  into  the 
hydrate  when  mixed  with  a  small  quantity  of  water,  heat 
being  evolved. 

Chloral  is  prepared  by  the  chlorination  of  alcohol  and 
subsequent  distillation. 

CHLORAMINE-T — An  antiseptic,  being  a  derivative  of  toluene, 
capable  of  generating  chlorine. 

CHLORANIL  (C6C14O2) — A  substance  which  crystallizes  in 
yellow  plates ;  used  as  an  oxidizing  agent  in  making  coal- 
tar  dyes. 

CHLORANILINES  —  Chlorinated  derivatives  of  aniline, 
C6H4C1NH2,  C6H3C12NH2,  and  C6H2C13NH2. 


CHLORIDE  OF  LIME—  CHLORINE  109 

CHLORIDE  OF  LIME—  See  Calcium  and  Chlorine. 

CHLORINE  (Cl)  and  its  compounds  —  Atomic  weight,  35-5; 
sp.  gr.,  2'49  ;  melting-point,  —  ioi'5°C.  Chlorine  is  not 
found  in  nature  in  an  uncombined  state,  but  exists  very 
extensively  in  combination  with  other  substances,  and 
most  abundantly  in  the  form  of  common  salt  —  sodium 
chloride  (NaCl).  There  are  large  deposits  of  salt  in 
Cheshire,  and  it  forms  part  of  the  well-known  Stassfurt 
saline  deposits  (in  Germany).  Combined  with  hydrogen  as 
hydrochloric  acid  (HC1),  it  is  a  natural  constituent  of  the 
gastric  juice  of  men  and  animals.  In  the  form  of  salt  it  is 
always  found  present  in  sea-  water  ;  thus,  the  water  of  the 
English  Channel  contains  28-05  parts  per  1,000.  Common 
salt  is  mined  to  some  extent  in  an  impure  state  in  the  dry 
condition  (rock  salt),  but  for  the  most  part  (being  soluble  in 
water)  it  is  made  by  pumping  water  into  the  salt  deposits 
and  subsequent  evaporation  of  the  brine  solution  thus 
prepared. 

Chlorine  in  gaseous  form  is  manufactured  on  a  large 
scale,  and  is  employed  chiefly  in  the  preparation  of  chloride 
of  lime,  or  bleaching  powder  (see  Calcium),  which  is  used 
for  bleaching  purposes  and  as  a  sanitary  reagent.  For  this 
purpose  it  is  mostly  made  by  the  action  of  hydrochloric  acid 
upon  manganese  dioxide  (see  Alkali  Trade  Chart,  p.  18): 

MnOa  +  4HC1  =  MnCl2  +  2  H2O  +  C12. 

In  the  Weldon  process,  the  manganese  is  reprecipitated 
from  the  resulting  manganese  chloride  liquor  as  manganese 
hydroxide  (MnH2O2)  by  treatment  with  milk  of  lime  and 
peroxidized  by  a  current  of  air,  ready  for  use  over  again. 

In  the  Deacon  process,  which  is  also  employed  on  a 
manufacturing  scale,  a  mixture  of  hydrogen  chloride  (HC1) 
gas  and  air  is  exposed  to  the  catalytic  influence  of  cupric 
chloride  distributed  over  a  widely  exposed  surface  at  a 
temperature  of  about  400°  C.,  chlorine  and  water  being 
produced  as  follows  : 


There  is  also  an  electrolytic  method  of  manufacturing 
chlorine  now  in  use,  consisting  in  the  direct  electrolysis  of 
a  solution  of  common  salt  (brine),  in  which  the  gas  is 
evolved  at  the  anode  whilst  sodium  hydrate  is  produced  at 
the  cathode.  The  concentrated  gaseous  chlorine  thus  pre- 
pared and  liquefied,  and  stored  in  iron  cylinders,  was  largely 
used  in  the  great  war  for  "  gassing  "  by  reason  of  its  cor- 
rosive and  poisonous  character. 


i  io  CHLORINE—HYDROCHLORIC  ACID 

CHLORINE  (Continued)— 

In  the  liquefied  form  it  is  of  a  bright  golden-yellow 
colour,  and  when  cooled  sufficiently  it  freezes  to  a  yellow 
crystalline  mass.  It  immediately  passes  into  the  gaseous 
state  when  liberated  in  the  air,  and  has  a  very  violent 
action  on  the  linings  of  the  mouth,  nose,  throat,  and  lungs, 
causing  death  when  inhaled  in  serious  quantity. 

On  account  of  its  sterilizing  value,  chlorine  as  such,  or  in 
the  form  of  bleaching  powder,  is  frequently  used  for  the 
purification  of  water-supplies. 

Chlorine  is  also  employed  in  the  manufacture  of  potas- 
sium chlorate  (KC1O8),  which  is  extensively  used  in  match- 
making and  in  the  preparation  of  certain  explosives  and  of 
chloroform. 

Chlorine  gas  is  of  a  greenish-yellow  colour,  and  nearly 
two  and  a  half  times  heavier  than  air.  It  is  somewhat 
soluble  in  water,  i  volume  of  which  at  10°  C.  absorbs 
3-1  volumes  of  chlorine,  forming  a  green  solution.  When 
strong  chlorine  water  is  cooled  to  nearly  freezing-point, 
it  deposits  a  crystalline  hydrate  (C128H2O)  of  unstable 
character. 

Metallic  copper  in  thin  leaf  form,  metallic  antimony  in 
the  form  of  a  powder,  and  sodium,  all  take  fire  and  burn 
readily  in  chlorine  gas,  forming  chlorides,  although  the  gas 
itself  is  not  inflammable.  Similarly  a  jet  of  burning  hydro- 
gen gas  will  burn  in  a  vessel  containing  chlorine  gas,  thus 
producing  hydrochloric  acid  in  the  form  of  white  fumes  : 

=  HC1. 


Hydrochloric  Acid,  or  hydrogen  chloride  (HC1),  is  one  of 
the  most  important  compounds  of  chlorine.  The  two  gases 
hydrogen  and  chlorine  do  not  combine  when  mixed  together 
in  the  dark,  but  in  sunlight  or  electric  light  they  combine 
with  explosive  violence.  The  acid  can  be  easily  prepared, 
amongst  other  methods,  by  the  action  of  strong  sulphuric 
acid  upon  common  salt  as  represented  by  the  equation  — 

2NaCl  +  H2SO4  =  Na2SO4  +  2HC1  ; 

that  is  to  say,  sodium  sulphate  and  hydrochloric  acid  are 
produced,  and  the  hydrochloric  acid  can  be  distilled  over 
from  the  mixture  in  the  form  of  gas  and  condensed  in  water, 
thus  furnishing  a  solution  of  the  acid.  In  its  gaseous 
form,  the  acid  is  colourless  and  possesses  a  pungent,  irrita- 
ting character.  It  is  soluble  in  water,  i  volume  of  which 
at  o°  C.  and  under  ordinary  atmospheric  pressure  dissolves 
503  volumes. 


CHLORINE— CHLORIC  ACID  in 

CHLORINE  (Continued)— 

Hydrochloric  acid  finds  use  in  the  textile  and  chrome 
tanning  industries,  and  the  manufacture  of  dyestuffs,  and 
is  obtained  as  a  by-product  in  the  manufacture  of  sodium 
carbonate  from  common  salt  and  sulphuric  acid,  the  gas 
(HC1)  being  absorbed  in  condensers  by  the  action  of  water 
percolating  down  towers  or  stacks  packed  with  broken  coke, 
up  which  it  is  led.  (See  Alkali  Trade.) 

Hydrochloric  acid  decomposes  the  oxides  and  carbonates 
of  the  alkaline  and  other  metals,  as  illustrated  by  the 
following  equations — the  first  representing  the  action  of 
the  acid  upon  sodium  oxide  (Na2O),  the  second  that  of  the 
acid  upon  barium  oxide  (BaO),  and  the  third  that  upon 
ferric  oxide — 

Na2O  +  2HCl=2NaCl  +  H2O, 

BaO  +  2HCl  =  BaCl2+H20, 

Fe203  +  6HC1  =2FeCl3  +  3H2O, 

the  chloride  of  the  base  being  produced  in  each  case.  Car- 
bonates of  the  same  and  many  other  bases  are  similarly 
decomposed.  For  instance,  using  sodium  carbonate  the 
change  is  as  follows  : 

Na2CO3  +  2HC1  =  2NaCl  +  H2O  +  CO2  ; 
and  barium  carbonate  as  follows  : 

BaCO3  +  2HC1  =  BaCl2  +  H2O  +  CO2. 

Hypochlorous  Acid  (HC1O)  is  only  known  in  association 
with  water,  in  which  it  is  soluble,  the  solution  being 
yellowish  in  colour  and  having  a  chlorous  odour.  It  can 
be  made  by  a  number  of  processes,  notably  by  the  action 
of  any  dilute  mineral  acid,  such  as  hydrochloric  acid  upon 
a  soluble  hypochlorite  such  as  a  solution  of  bleaching 
powder.  Strong  solutions  of  the  acid  are  unstable  and  apt 
to  decompose  with  violence,  but  a  dilute  one  is  more  stable 
and  exhibits  powerful  oxidizing  and  bleaching  effects. 

Sodium  Hypochlorite  (NaCIO)  in  solution  is  used  as  a 
sanitary  reagent,  and  more  extensively  for  oxidizing  and 
bleaching  purposes. 

Chloric  Acid  (HC1O3)  is  prepared  by  the  action  of  dilute 
sulphuric  acid  upon  barium  chlorate,  but  it  also  is  only 
known  in  association  with  water,  as  a  stronger  solution 
than  80  per  cent,  decomposes,  upon  heating,  into  chlorine 
and  water.  It  is  a  powerful  oxidant,  wood  and  paper  being 


ii2  CHLORINE— CHLORITE 

CHLORINE  (Continued)— 

liable  to  combustion  when  a  strong  solution  is  dropped  upon 
them.  The  potassium  salt  (KC1O3) — potassium  chlorate — 
is  an  important  article  of  commerce,  and  was  originally 
made  by  the  action  of  chlorine  upon  milk  of  lime  by  which 
calcium  chlorate  is  ultimately  formed — 

6Ca(HO)2  +  6C12  =  Ca(ClO3)2  +  5CaCl2  +  6H2O  ; 

and  in  a  subsequent  operation  the  calcium  chlorate  was 
converted  into  the  potassium  salt  by  treatment  with  potas- 
sium chloride  and  crystallized  out  from  the  mixture — 

Ca(C103)2  +  aKCl  =  2KC103  +  CaCl2. 

This  process,  however,  has  been  superseded  by  an 
electrical  one  in  which  potassium  chloride  is  directly 
transformed  into  the  chlorate  by  the  action  of  the  electrical 
current  upon  a  solution  at  a  temperature  of  50°  C. 

Potassium  chlorate  crystallizes  in  white  tables,  is  soluble 
in  water  to  the  extent  of  3*3  per  cent,  at  o°  C.  and  59  per 
cent,  at  100°  C.,  and  is  largely  used  in  the  manufacture  of 
explosives,  percussion  caps,  matches,  and  in  pyrotechnics. 

When  heated  to  380°  C.  it  melts  and  gives  off  oxygen, 
and  this  affords  one  method  of  obtaining  that  gas. 

CHLORINATION — The  name  given  to  any  process  by  which 
chlorine  is  imported  into  a  substance ;  for  example, 
lime  is  converted  into  bleaching  powder,  or  so-called 
chloride  of  lime,  by  the  action  of  chlorine,  and  some 
additive  and  many  substitution  products  are  derived  from 
benzene  hydrocarbons  by  the  introduction  of  chlorine, 
hydrogen  being  replaced  by  chlorine  in  the  last-named 
instances.  Thus  benzene  hexachloride  (C6H6C16)  is  an 
additive  substance  produced  by  exposing  benzene  to  chlorine 
gas  for  a  prolonged  period,  etc.  Methyl  chloride  (CH3C1) 
illustrates  the  chlorination  act  by  which  hydrogen  is  replaced 
by  chlorine,  and  is  obtained  with  other  substances  when 
chlorine  is  permitted  to  act  on  methane  (marsh  gas,  CH4). 
In  the  preparation  of  benzyl  chloride  from  boiling  toluene  by 
the  action  of  chlorine,  the  following  interaction  takes  place : 

C7H8+C12  =  C7H7C1  +  HC1. 

CHLORITE — A  mineral  hydrated  double  silicate  of  aluminium 
and  magnesium  coloured  with  iron,  often  found  in  associa- 
tion with  garnet,  quartz,  and  calcite. 


"  CHLORODYNE  "-CHOLINE  113 

"  CHLORODYNE  " — A  pharmaceutical  compound  containing 
prussic  acid,  morphia,  chloroform,  and  hemp,  having  proper- 
ties of  an  opiate  and  an  antispasmodic. 

CHLOROFORM  (CHC13)— A  halogen  substitution  product  con- 
stituting  a  volatile,  valuable  anaesthetic  liquid,  prepared 
from  acetone  or  alcohol  by  the  action  of  chloride  of  lime 
and  water.  It  is  also  a  useful  solvent  of  fats  and  other 
substances,  boils  at  61-2°  C.,  has  a  sp.  gr.  of  1*499,  and  is 
soluble  in  alcohol  and  ether. 

CHLOROPHYLL — The  green  colouring  matter  of  the  leaves 
and  other  parts  of  plants  which  is  only  developed  when 
plants  are  grown  in  the  light.  So  far  as  investigation  has 
gone  it  would  appear  to  be  a  magnesium  compound  of  the 
formula  Mg,C55H72N4O5  or  Mg,C55H72N4O6,  and  there 
seems  to  be  some  relationship  between  it  and  the 
colouring  matter  of  the  blood.  It  is  associated  in  leaves 
with  two  other  colouring  matters — viz.,  carotin  (carrotene), 
the  substance  which  gives  its  colour  to  carrots  (said  to  be 
a  hydrocarbon  of  the  formula  C40H56),  and  xanthophyll,  a 
substance  of  dark  brownish-red  tint  (said  to  have  the  com- 
position C40H56O2,  and  to  be  an  oxidation  product  of 
carotin). 

Chlorophyll  itself  is  stated  to  be  a  mixture  of  two  sub- 
stances, differing  in  their  spectra  and  solubility  in  certain 
solvents.  (See  also  Plant  Colouring  Matters.) 

"  CHLOROS  "—The  trade  name  of  a  proprietary  disinfectant 
solution  containing  sodium  hypochlorite. 

CHOKE-DAMP — A  mixture  of  carbon  dioxide  and  other 
poisonous  gases  met  with  in  coal-workings,  particularly 
after  explosions. 

CHOLALIC  ACID  (C24H40O5)— See  Taurocholic  Acid  and  Bile. 

CHOLESTEROL  (Cholesterine)  (C26H44O)— A  white,  inodorous 
substance  which  crystallizes  with  water  (C26H44O,H2O)  in 
beautiful  pearly  plates,  is  insoluble  in  water  but  soluble  in 
ether  and  hot  alcohol,  and  melts  at  i48'5°  C.  It  enters 
into  the  composition  of  gall-stones,  the  human  bile,  brain 
and  nerve  substance,  being  present  in  bile  to  the  extent  of 
about  0*25  per  cent,  and  in  brain-matter  to  about  i  per 
cent.  It  can  be  sublimed  without  decomposition  at  about 
300°  C.  in  vacuo.  Its  formula  is  sometimes  expressed  as 
C27H45OH  +  H20. 

CHOLINE  (C5H15NO2)— A  basic  substance  nearly  related  to 
neurine, 

8 


1 14  CHONDRINE— CHROMIUM 

CHONDRINE — An  albuminous  substance  resembling  gelatine, 
produced  by  boiling  certain  animal  tissues,  such  as  cartilages, 
with  water. 

CHONDRUS— See  Agar-Agar. 

CHRISTOBALITE — A  crystallized  form  of  silica,  frequently 
found  in  volcanic  rocks. 

CHROMATES — See  Chromium. 
CHROME  ALUM— See  Alum  (Chrome). 
CHROME  IRON — See  Chromium. 

"  CHROMETAN  " — A  proprietary  reduced  chrome  made  in 
liquid  and  crystalline  forms  for  use  by  tanners.  The  ordinary 
liquid  has  a  basicity  of  144°,  and  the  "  basic  "  variety  one 
of  96° ;  when  dried,  the  crystalline  variety  contains  25  per 
cent,  oxide  of  chromium. 

CHROMIC  ACID — See  Chromium. 

CHROMIUM  (Cr)  and  its  compounds — Atomic  weight,  52 ; 
sp.  gr.,  6-92  ;  melting-point,  1,615°  C.  Chromium  occurs 
in  nature  in  combination  in  a  number  of  minerals,  including 
chrome  iron  ore  or  chromite  (Cr2O3FeO),  the  main  source 
of  preparation  of  chromium,  large  supplies  of  which  come 
from  New  Caledonia,  Rhodesia,  U.S.A.,  and  Canada.  It 
also  occurs  in  the  forms  of  lead  chromate  or  crocoisite 
(PbCrO4)  and  chrome  ochre  (Cr2O8).  The  higher  grades  of 
chromite  contain  from  40  to  50  per  cent,  of  the  oxide,  and 
considerable  quantities  are  mined  in  California  and  Oregon 
(U.S.A.),  in  Portuguese  Africa,  and  French  Oceania.  There 
are  also  good  deposits  in  Cuba,  and  it  is  put  to  use,  among 
other  applications,  in  the  manufacture  of  chromite  bricks 
for  metallurgical  use  in  lining  furnaces. 

In  the  metallic  state,  chromium  is  a  hard,  steel-grey 
metal,  and  is  employed  for  the  purpose  of  imparting  hard- 
ness and  tenacity  to  steel  used  for  making  tyres,  springs, 
axles,  and  armour-plate,  by  incorporation  of  from  0-5  to 
3  per  cent.  It  is  as  hard  as  corundum. 

The  metal  is  manufactured  from  its  oxide  by  intensely 
heating  a  mixture  of  it  with  powdered  metallic  aluminium, 
which  combines  with  the  oxygen  to  form  alumina  (A12O3), 
metallic  chromium  being  set  free  in  a  molten  condition. 

There  are  two  oxides,  Cr2O3  (chrome  green)  and  CrO3, 
the  former  of  which,  known  as  chromium  sesquioxide,  is  used 
as  a  green  pigment  and  the  other  (chromic  anhydride) 
constitutes  the  colouring  matter  of  the  ruby,  and  can  be 


CHROMIUM—  CHRYSENE  115 

CHROMIUM  (Continued)— 

obtained  in  red,  needle-shaped  crystals.  When  heated  to 
250°  C.  it  gives  off  oxygen,  and  is  converted  into  the 
lower  oxide — 

2CrO3=Cr2O3  +  3O. 

It  is  a  powerful  oxidant,  and  when  dissolved  in  water  is 
supposed  to  produce  chromic  acid  (H2CrO4). 

Potassium  Chromate  (K2CrO4)  is  a  yellow  crystalline 
body,  soluble  in  water ;  whilst  the  dichromate  (K2Cr2O7), 
which  is  also  soluble  in  water,  crystallizes  in  red  prisms, 
and  is  manufactured  on  a  large  scale,  not  merely  on  account 
of  its  uses  in  tanning,  bleaching,  and  as  an  oxidizing  agent, 
but  chiefly  for  the  preparation  of  the  various  well-known 
chrome  pigments,  including  "chrome  yellow,"  or  lead 
chromate(PbCrO4).  It  also  finds  some  use  in  photography, 
as  when  a  film  of  gelatine  is  treated  with  a  solution  of 
that  substance  it  is  rendered  insoluble  by  the  chemical 
change  that  ensues. 

Sodium  Bichromate  is  also  used  to  some  extent  in  certain 
processes  for  tanning  leather. 

Chromium  Borate  is  used  as  a  pigment  in  calico-printing. 

Other  chromium  compounds  include : 

Chromium  chloride  (CrCl8)  and  its  hydrate  (CrCl36H2O), 
which  is  soluble  in  water  and  used  as  a  mordant ; 

Chromium  phosphate  (CrPO4)  (Plessy's  green),  insoluble 
in  water  and  used  as  a  pigment ; 

Chromium  sulphate  (Cr2(SO4)3)  and  its  hydrate 
(Cr2(SO4)315H2O),  the  former  being  insoluble,  but  the 
second  soluble  in  water  and  used  in  the  textile  trades ; 

Chromium  potassium  sulphate  (K2SO4,Cr2(SO4)3.24H2O), 
a  violet-red  crystalline  salt,  soluble  in  water,  used  as  a 
chrome  tan  liquor  and  in  the  textile  industry  (see  Alum 
chrome) ;  and 

Chromium  acetate  (Cr(C2H3O2)3.H2O),  a  greenish  powder 
soluble  in  water,  also  used  in  the  textile  trades. 

CHRYSAMINE— A  substantive  yellow  coal-tar  dye  used  in 
the  leather  and  textile  trades,  prepared  from  salicylic  acid. 

CHRYSENE  (C18H12) — A  white  crystalline  hydrocarbon  con- 
tained in  the  coal-tar  distillate  which  comes  over  above 
360°  C.  It  melts  at  250°  C.,  boils  at  448°  C.,  and  resembles 
anthracene  in  properties. 


1 1 6  CHRYSOBERYL— CINCHONA 

CHRYSOBERYL— A  natural  combination  of  the  oxides  of 
aluminium  and  beryllium  (Al2O3BeO). 

CHRYSOIDINE  —  An  orange-red  colour  which  dyes  silk  and 
wool  directly.  It  is  a  hydrochloride  of  diamido-azobenzene 
(C6H5N2,C6H3(NH2)2HC1),  and  is  slightly  soluble  in 
water. 

CHRYSOLITE  (Peridot,  Fibrous  serpentine) — Natural  crystals 
of  olivine  (magnesium  silicate). 

CHRYSOPHANIC  ACID  (Chrysarobin)  (C30H26O7)— A  medi- 
cinal body  prepared  from  Araroba  (Goa  powder),  which  is 
deposited  in  the  wood  of  Vouacapoua  araroba.  It  is  soluble 
in  water,  alcohol,  and  ether,  and  melts  at  157°  C. 

CHYLE — The  digested  alkaline  fluid  resulting  from  the  con- 
version of  chyme  by  action  of  the  biliary  and  pancreatic 
juices,  being  thus  prepared  ready  for  absorption  by  the 
lacteals  of  the  intestines  and  conversion  into  blood. 

CHYME — The  stomach-digested  food  before  it  is  acted  upon 
by  the  bile  and  pancreatic  juice. 

CIDER — Fermented  juice  of  apples,  containing  from  5  to  9 

per  cent,  alcohol. 
CIMOLITE — A  hydrous  mineral  aluminium  silicate. 

CINCHONA  (Peruvian  bark,  Loxa  bark,  Red  Peruvian  bark, 
etc.) — The  bark  of  the  stems  and  branches  of  various 
species  of  cinchona  and  other  genera  of  the  Rubiacea  order, 
growing  in  the  Cordilleras  and  elsewhere  between  the 
latitudes  10°  N.  and  19°  S.  The  chief  supplies  are  obtained 
from  Java,  India,  and  Ceylon.  The  output  of  quinine  from 
the  Indian  factories  for  the  three  years  1916-18  reached 
an  average  of  64,000  Ib.  per  annum.  A  number  of  im- 
portant bases  or  alkaloids  are  contained  in  these  barks,  includ- 
ing quinine  (C20H24N2O2.3H2O),  cinchonine  (C19H22N2O), 
quinidine  (C20H24N2O2),  and  cinchonidine  (C19H22N2O), 
the  two  last  named  being  regarded  as  probably  stereoiso- 
meric  with  the  two  former. 

Quinine  is  a  white,  crystalline  alkaloid,  which  melts  at 
177°  C.,  is  soluble  in  alcohol  and  ether,  and  is  intensely 
bitter.  The  sulphate  and  chloride  are  both  used  as  febri- 
fuges and  otherwise  in  medicine,  as  also  the  acetate, 
benzoate,  phosphate,  salicylate,  tartrate,  tannate,  citrate, 
and  glycerophosphate.  The  sulphate  is  a  white,  crystalline 
powder  soluble  in  water  to  the  extent  of  i  in  350  parts, 
has  a  bitter  taste,  and  in  solution  exhibits  a  strong 
fluorescence. 


CINCHONA—  CINNAMIC  ACID  117 

CINCHONA  (Continued)— 

Ninety-seven  per  cent,  of  the  world's  production  of 
quinine  is  obtained  from  Java  cinchona  bark,  although  the 
resources  of  the  British  Empire  are  sufficient,  if  utilized,  to 
be  independent  of  Holland. 

One  method  of  preparing  quinine  consists  in  mixing  the 
finely  ground  bark  with  powdered  lime  and  extracting  the 
mixture  with  hot  high-boiling  paraffin  oil,  and,  after  filtra- 
tion, shaking  the  filtrate  with  dilute  sulphuric  acid.  The 
acid  solution  is  then  neutralized  with  sodium  carbonate 
solution,  and  upon  cooling  the  quinine  sulphate  crystallizes 
out.  The  alkaloid  can  be  obtained  from  the  sulphate  by 
treatment  with  ammonia. 

Cinchonine  is  a  white,  crystalline  body,  slightly  soluble  in 
water,  alcohol,  and  ether,  with  a  melting-point  of  2643°  C. 
The  hydrochloride,  nitrate,  and  sulphate  are  all  soluble  in 
water  and  alcohol. 

Cinchonidine  is  a  white,  crystalline  body,  soluble  in 
alcohol,  of  melting-point  207*2°  C. 

Conchinine  (Quinidine)  is  colourless  and  crystalline,  of 
efflorescent  character,  and  is  soluble  in  alcohol  and  ether, 
having  a  melting-point  of  171*5  C. 

All  the  antifebrile  barks  are  used  medicinally  in  the  form 
of  tinctures  and  infusions,  on  account  of  their  valuable 
febrifuge  and  tonic  properties,  as  are  also  those  of  the 
separated  alkaloids  and  their  sulphates. 

CINCHONIDINE— See  Cinchona. 
CINCHONINE— See  Cinchona. 

CINEOL  (C10H18O),  otherwise  known  as  cineole  and  eucalyptol, 
is  found  in  many  essential  oils,  and  is  the  predominating 
constituent  of  the  oils  of  cajuput,  wormseed,  and  Eucalyptus 
globulus.  It  is  derived  from  terpin  hydrate  (C10H22O3)  by 
dehydration,  and  is  a  colourless  liquid  of  characteristic 
camphoraceous  odour,  soluble  in  ether,  with  a  sp.  gr.  of 
0*9267,  boiling-point  176°  C.,  and  melting-point  -  i°  to  3°  C. 

CINNABAR — Native  sulphide  of  mercury,  a  deposit  of  which 
has  recently  been  discovered  in  the  Aguas  Blancas  district, 
in  Chile,  near  Antofagasta. 

CINNAMIC  ACID  (C9H8O2)— A  white,  crystalline  derivate  of 
benzene  found  present  in  Peru  and  Tolu  balsams,  and 
liquid  storax,  soluble  in  alcohol,  ether,  and  hot  water,  and 
which  yields  benzoic  acid  upon  oxidation.  It  is  monobasic, 


ri8  CINNAMIC  ACID— CITRATES 

CINNAMIC  ACID  (Continued)— 

melts  at  133°  C.,  and  forms  a  large  variety  of  crystallizable 
salts. 

CINNAMIC  ALCOHOL  (Styrone  or  Cinnamyl  alcohol) 
(C6H5CH:CH:CH2OH)  crystallizes  in  white  needles,  is 
soluble  in  alcohol  and  ether,  has  an  odour  like  that  of 
hyacinths,  and  is  used  in  perfumery.  It  occurs  as  cinnamic 
ester  (styracin)  in  storax,  and  is  prepared  from  that  sub- 
stance by  the  action  of  potassium  hydroxide,  followed  by 
distillation.  Its  sp.  gr.  is  1*0397,  and  it  boils  at  257°  C. 
By  oxidation  it  yields  cinnamic  acid,  and  when  the  oxidation 
is  more  vigorous,  benzoic  acid. 

CINNAMIC  ALDEHYDE  (Q,H8O)— An  aromatic  oily  body 
which  boils  at  246°  C.,  forming  the  chief  constituent  of 
cinnamon  oil  (from  Persea  cinnamomum). 

CINNAMON — The  inner  bark  of  trees  of  the  genus  cinnamomum 
which  grow  in  Ceylon,  and  is  a  well-known  spice,  which 
yields  from  \  to  i  per  cent,  of  the  essential  oil  of  cinnamon, 
which  is  prepared  from  it  by  distillation,  using  salt  water, 
and  contains  cinnamic  aldehyde  (C9H8O)  and  eugenol.  The 
oil  possesses  an  aromatic  pleasant  odour  and  taste,  and  is 
used  for  flavouring  and  medicinally  as  a  stimulant.  It  has 
a  sp.  gr.  i '024  to  1*04,  refractive  index  1*59  to  i'6o,  and 
a  rotation  of  o°  to  i°. 

Cinnamon  leaf  oil  is  distilled  from  the  leaves  of  the 
Cinnamomum  zeylanicum.  It  is  pale  yellow,  having  a  charac- 
teristic spicy  odour,  contains  cinnamic  aldehyde  and  safrol, 
has  a  sp.  gr.  of  1*044  to  I<O65,  refractive  index  1*535,  and 
optical  rotation  o°  5'  to  +  i°,  and  is  used  for  flavouring, 
etc. 

CITRAL  (or  GERANIAL)  (C10H16O)— An  aldehydic  body 
found  in  the  oils  of  lemon,  oranges,  and  lemon-grass,  the 
last  named  of  which  contains  from  70  to  80  per  cent.  It  is 
a  colourless  oil,  which  may  also  be  obtained  by  the 
oxidation  of  geraniol,  which  is  its  corresponding  alcohol 
(C10H18O),  and  which  forms  the  chief  constituent  of  Indian 
geranium  oil. 

CITRATES  of  the  alkalies  are  soluble  in  water. 

Calcium  Citrate,  which  can  be  prepared  by  adding  an 
alkali  citrate  solution  to  one  of  calcium  chloride,  is  a  white 
powder  insoluble  in  water. 

Citrate  of  Iron  and  Ammonia — A  pharmaceutical  pre- 
paration used  as  a  tonic. 


CITRATES— CLAYS  119 

CITRATES  (Continued) — 

Citrate  of   Iron  and  Quinine — A  pharmaceutical    pre- 
paration used  as  a  tonic. 

CITRENE— See  Terpenes. 

CITRIC  ACID  (C6H8O7) — Occurs  naturally  in  many  fruits, 
including  lemons,  citrons,  oranges,  and  red  bilberries,  and 
associated  with  malic  acid  in  gooseberries.  It  is  also  found 
as  calcium  citrate  in  potatoes,  beetroot,  etc.  Lemon-juice 
is  the  material  from  which  it  is  usually  made,  and  when 
pure  it  crystallizes  in  large,  colourless,  rhombic  prisms  (in 
association  with  water),  which  melt  at  153°  C.  and  are 
readily  soluble  in  water.  Citric  acid  and  its  salts  are  used 
in  medicine,  in  the  preparation  of  summer  drinks,  and  ex- 
tensively in  dyeing  and  calico-printing.  Citric  acid  is  also 
used  as  a  remedy  for  scurvy. 

CITRONELLA  OIL  (Lana  batu)  —  A  limpid,  yellowish  to 
yellowish- green  essential  oil  distilled  from  the  grass  of  a 
species  of  Andropogan,  which  yields  from  J  to  i  per  cent. 
It  contains  geraniol,  citronellal,  and  methyl  eugenol;  is 
soluble  in  alcohol,  ether,  etc. ;  has  a  sp.  gr.  of  0-9,  refractive 
index  1-4811  to  1-4830,  and  optical  rotation  -5°  to— 21°. 
It  is  used  in  the  perfumery  trade,  for  scenting  soap,  and  as 
an  insectifuge. 

The  Ceylon  oil  is  of  much  the  same  character  and  is 
distilled  from  the  fruit  of  Tetranthem  citrata. 

CIVET — An  unctuous  secretion  from  the  civet  cat,  soluble  in 
hot  alcohol  and  ether,  used  in  perfumery. 

CLAMPS — Fasteners  or  clasps  of  various  descriptions  accord- 
ing to  their  intended  use,  including  flask-clamps,  burette- 
clamps  (see  Burette),  and  clamps  to  hold  Liebig's  condensers. 
(See  Retort.) 

CLAYS — Natural  hydrated  compounds  of  alumina  and  silica  (sili- 
cate of  alumina)  resulting  from  the  combined  action  of  air  and 
water  upon  certain  felspathic  rocks.  When  heated  to 500°  C., 
clay  is  decomposed  into  free  silica,  alumina,  and  water. 

China  Clay,  as  mined  in  Cornwall  on  a  large  scale,  is  said 
to  be  chiefly  produced  by  the  disintegration  of  the  rock 
known  as  pegmatite — a  kind  of  granite — and  is  much  used 
in  making  pottery  and  stoneware.  The  tedious  process  of 
sedimentation  attendant  upon  the  treatment  by  levigation 
of  this  material  can  be  hastened  by  electrical  means,  the 
clay  being  mixed  with  water  and  some  alkali,  and  then 
subjected  to  an  electric  current,  by  which  means  the  im- 


120  CLAYS— CLOVES 

CLAYS  (Continued)— 

purities  (mica,  felspar,  quartz,  and  iron  compounds)  are 
either  precipitated  or  migrate  to  the  cathode,  whilst  the 
purified  clay  has  better  agglomeration,  is  more  plastic,  and 
moulds  better.  This  "  osmosed  clay,"  being  purer  than 
that  produced  by  the  ordinary  process,  can  be  used  in 
making  porcelain  of  high  quality.  Porcelain  is  made  non- 
porous  by  glazing. 

Pipeclay,  another  variety,  is  largely  used  in  making  clay 
tobacco-pipes. 

Fireclay,  as  used  to  make  fire-bricks,  is  a  natural  mixture 
of  kaolin  or  china  clay  mixed  with  sand  as  found  beneath 
certain  coalbeds,  and  is  almost  infusible.  The  fireclay  is 
moulded  into  brick  form  and  then  burned  at  a  very  high 
temperature.  (See  also  Refractories  and  Silica.) 

Lime,  magnesia,  iron  oxide,  and  other  substances  are 
generally  associated  with  the  various  clays,  and  it  is  due  to 
the  presence  of  iron  that  ordinary  clay  turns  red  upon  burning 
into  "  ballast." 

It  is  the  ordinary  common  clay  or  loam  that  is  employed 
in  the  manufacture  of  bricks,  tiles,  and  coarse  pottery,  whilst 
selected  clays  are  used  in  the  manufacture  of  Portland  and 
other  cements.  (See  Cements.) 

Clay  prepared  in  a  colloidal  form  is  used  as  a  soap  in  wool 
scouring,  owing  to  its  capacity  of  absorbing  dirt  and  grease, 
and  removing  unsaponifiable  oily  matters,  but,  of  course,  it 
has  the  disadvantages  of  being  insoluble,  and  does  not 
hydrolize  like  ordinary  soaps,  which  are  also  used  for 
similar  applications. 

CLEVEITE — A  mineral  containing  occluded  helium. 

CLOCK-GLASSES — Shallow  concave  glasses  of  various  sizes 
used  in  laboratories  for  covering  beakers  and  dishes,  and 
for  testing  purposes. 

CLOVES — The  undeveloped  flower  buds  of  the  clove-tree 
(Eugenia  caryophyllata)  used  as  a  spice,  which  yield  from  15 
to  20  per  cent,  of  the  essential  oil  of  cloves  as  obtained  by 
distillation  of  the  buds  and  flower  stalks  with  water.  It  is 
a  pale  yellow,  pungent-smelling  liquid  containing  from  85  to 
90  per  cent,  of  eugenic  acid  or  eugenol  (C10H12O2),  and  a 
small  quantity  of  a  terpene  isomeric  with  turpentine.  It 
boils  at  251°  C. ;  its  sp.gr.  is  1-048  to  1*070,  refractive  index 
1*528  to  1*540,  and  rotation  o°  to  1-30°.  It  is  soluble  in 
alcohol  and  ether,  and  is  used  for  flavouring  and  for  the 
relief  of  toothache. 


CLOVES— COAL 


121 


CLOVES  (Continued)— 

Eugenol  was  found  during  the  recent  war  to  be  of  great 
service  in  preparing  plastic  and  transparent  varnishes,  of 
which  aceto- cellulose  was  the  base,  for  covering  wings  of 
aeroplanes.  It  is  also  of  value  as  a  source  of  vanillin, 
which  is  prepared  from  it  by  oxidation. 

COAL  is  supposed  to  be  the  residual  product  of  the  natural  de- 
composition of  forests  and  other  vegetable  matters  during 
enormous  periods  of  time,  and  is  a  very  complex  mixture  of 
carbon  compounds,  containing  generally  some  proportion 
of  nitrogen. 

It  is  an  indefinite  and  variable  mixture  of  compounds 
insoluble  in  pyridine,  cellulosic  compounds  soluble  in 
pyridine  but  insoluble  in  chloroform,  and  another  con- 
stituent of  resinoid  character  which  can  be  extracted  by 
certain  solvents,  such  as  pyridine,  and  chloroform,  while 
upon  the  relative  proportion  of  these  bodies  the  technical 
value  and  industrial  applications  depend. 

The  following  analysis  of  certain  coals  recently  published 
by  S.  Roy  Illingworth  are  given  as  some  illustrations  of 
their  composition,  which  varies  greatly : 


No.  2 
Llantuit. 

No.  3 
Rhondda. 

No.  2 
Rhondda. 

Per  Cent. 

Per  Cent. 

Per  Cent. 

Volatile  matters 

37-06 

3I'5° 

21-16 

Fixed  carbon  ... 

57*53 

66-93 

71*20 

Ash      

5'4J 

IJ57 

774 

On  dry  ash-free  coal  : 

C      

82-87 

8670 

87-96 

H      

5'8o 

5-00 

4*35 

O      ... 

776 

6-21 

4-32 

N      

1-49 

i'45 

1-42 

S      

2-08 

0-64 

i'95 

The  No.  2  Llantuit  coal  is  used  for  gas-making  and 
yields  a  very  porous  coke. 

The  No.  3  Rhondda  coal  is  carbonized  to  produce  a 
metallurgical  coke,  which  is  dense. 

The  No.  2  Rhondda  coal  is  a  "  hard-coking  "  coal,  and 
also  yields  a  dense  coke. 

Deposits  of  coal  are  found  in  all  parts  of  the  world,  and 
China  is  particularly  rich,  her  coalfields  being  regarded  as 
practically  inexhaustible. 


122  COAL 

COAL  (Continued)— 

It  has  been  ascertained  that  coal  undergoes  oxidation  by 
air,  one  experimental  result,  which  has  been  published, 
showing  a  gain  of  3*5  per  cent,  by  weight  in  one  month  at 
100°  C. 

Aniline  used  as  a  solvent  is  stated  to  furnish  a  means  of 
differentiating  between  grades  of  coal ;  the  "  fat  "  varieties 
yielding  a  relatively  higher  percentage  of  soluble  matter  as 
compared  with  the  "lean"  kinds.  The  soluble  part  is 
richer  in  hydrogen,  poorer  in  ash,  and  gives  a  better  coke 
than  the  insoluble  part. 

There  are  many  varieties,  and  they  are  roughly  divided 
into  hard  and  soft  coals,  the  softer  ones  being  used  for  fires 
and  gas-making,  while  the  harder  ones  contain  more  carbon, 
give  out  more  heat  when  burning,  and  are  consequently  more 
useful  for  steam-raising.  Bituminous  coal  contains  from 
50  to  80  per  cent,  of  carbon,  and  anthracite  from  85  to  95 
per  cent.  In  burning,  coal  may  be  said  to  give  back  the 
heat  and  light  which  were  originally  taken  from  the  sun  by 
the  plant-life  from  which  coal  is  produced. 

When  burned  or  roasted,  the  products  of  its  destructive 
decomposition  thus  effected,  vary  according  to  the  tempera- 
ture employed  and  the  proportion  of  air  that  gains  access 
to  the  burning  mass,  It  begins  to  yield  free  carbon  at 
about  500°  C.,  although,  of  course,  below  this  temperature 
decomposition  proceeds,  and  it  seems  probable  that  the 
formation  of  this  free  carbon  is  due  to  the  decomposition  of 
the  cellulosic  constituents  of  the  coal. 

About  190  million  tons  of  coal  are  annually  consumed  in 
the  United  Kingdom,  of  which  about  one-fifth  part  is  car- 
bonized in  gasworks  or  in  coke-ovens  (for  the  manufacture 
of  metallurgical  coke),  and  the  total  estimated  output  of  coal 
in  the  United  Kingdom  in  1919  was  about  230  million  tons. 

As  used  for  gas-making — so  that  it  is  not  allowed  to 
burn — coal  yields,  in  addition  to  the  gas,  watery  ammoniacal 
liquor  and  tar  which  pass  over  in  a  vaporous  condition 
and  are  condensed,  leaving  coke  in  the  retorts.  The  coal 
tar,  which  has  a  sp.  gr.  of  about  IT  to  1-2,  is  afterwards 
distilled  in  large  iron  retorts  heated  by  fire  and  yields  an 
average  per  ton  of  approximately  5  gallons  ammoniacal 
liquor,  6  gallons  crude  naphtha,  26  gallons  light  oils, 
17  gallons  creosote  oil,  38  gallons  anthracene  oils,  and 
12  cwt.  pitch  (left  behind  in  the  retorts),  which  is  run 
out  whilst  hot  and  semi-fluid.  It  is  from  these  primary 
distillates  of  coal  tar  that  so  many  explosives,  drugs,  dyes, 
and  disinfectants  are  produced. 


COAL  f23 

COAL  (Continued) — 

The  temperatures  at  which  these  several  distillates  are 
obtained  and  the  products  which  are  eventually  obtained 
from  them  may  be  expressed  as  follows  : 

1.  Ammonia  liquor  comes  over  up  to  about  150°  C. 

2.  Light    oil    (containing    carbolic    and    cresylic    acids, 
solvent  naphtha,  benzene,  and  toluene)  at  from   150°  C. 
to  220°  C. 

3.  Creosote  oil  (containing  naphthalene)  at  from  220°  C. 
to  280°  C. 

4.  Anthracene  oil  or  "  yellow  oil "  (parent  of  alizarin)  at 
from  280°  C.  to  350°  C. 

5.  Pitch  left  in  the  retorts  equal  to  about  60  per  cent,  of 
the  whole  tar,  which  is  said  to  contain  in  all  some  200  different 
organic  compounds. 

This  may  be  shown  diagrammatically,  as  follows : 


Coal. 
1 

G'a, 

Tar. 

I 

Coke. 

Ammonia.        Naphtha. 

1 
Creosote 
(or  green 
oil). 

Naphtha- 
lene (on 
cooling). 

Anthracene    Pitch, 
oil. 

Anthracene 
(on  cooling). 

Benzene.     Toluene.     Solvent 
naphtha 
(containing 
xylene). 

1 
Carbolic 
and 
cresylic 
acids. 

Over  1,500,000  tons  of  tar  are  annually  carbonized  in 
British  coke-ovens. 

It  has  been  stated  that  by  carbonizing  raw  coal  by  one 
method  at  a  low  temperature,  i  ton  is  converted  into : 
(a)  About  7,000  cubic  feet  of  gas  of  600  B.T.U.  (British 
thermal  units)  per  cubic  foot ;  (b)  about  3  gallons  of  light 
oil  (motor  spirit  or  petrol) ;  (c)  about  16  gallons  of  heavy 
oil  (like  crude  petroleum)  ;  (d)  about  20  Ib.  of  ammonium 
sulphate ;  and  (e)  about  14  cwt.  of  smokeless  fuel,  reported 
to  be  cheaper  and  more  efficient  than  raw  coal  for  domestic 
and  commercial  uses. 

In  round  numbers,  a  ton  of  average  coal  produces,  by 
direct  combustion,  30,000,000  British  thermal  units,  of 
which  in  the  best  steam-engine  practice  about  19  per  cent, 
can  be  obtained  as  power. 

Apart  from  the  employment  of  creosote  for  impregnating 
timber  (sleepers,  etc.),  the  life  of  which  it  prolongs,  the 
tar  acids  are  extracted  from  naphtha  and  creosote  by  means 


124 


COAL 


COAL  (Continued)— 

of  soda.     Pyridine  is  also  extracted  from  them  by  treat- 
ment with  sulphuric  acid. 

Anthracene  is  used  in  the  manufacture  of  aniline  colours 
which,  used  as  dyes,  are  of  great  value  in  the  textile  and 
other  large  industries. 

When  the  express  object  of  distilling  coal  is  to  obtain 
coke  for  use  in  connection  with  the  production  of  iron  and 
steel,  it  is  now  coked  in  specially  constructed  ovens.  The 
coke  which  is  obtained  amounts  to  about  from  60  to  70  per 
cent,  of  the  coal  used ;  the  tar  and  ammonia  are  recovered, 
and  the  gas  which  is  generated  is  burned  in  such  a  way  as 
to  assist  in  heating  the  ovens,  or  otherwise  utilized. 

Tar  and  ammonia  are  also  recovered  from  blast  furnaces 
in  which  coal  and  coke  are  used  in  the  manufacture  of  iron 
and  steel,  but  the  products  obtained  from  the  tar  vary  from 
those  obtained  from  gas  tar.  Among  these  is  a  quantity 
of  so-called  phenoloids,  or  homologues  of  cresol,  of  much 
greater  antiseptic  and  germicidal  power  than  carbolic  and 
cresylic  acids,  and  they  are  largely  used  in  the  preparation 
of  disinfectants. 

The  following  information  is  taken  from  a  work  on  coal 
tars  recently  published  by  Dr.  G.  Malatesta  (E.  and  F.  N. 
Spon,  Ltd.). 

Coke-furnace  tar  is  distinguished  from  that  of  illuminat- 
ing gas  by  a  lower  amount  of  free  carbon  and  the  different 
amounts  of  the  various  compounds. 

The  free  carbon  of  coke-furnace  tar  does  not  exceed,  as 
a  rule,  10  to  12  per  cent.,  and  frequently  the  content  is 
between  2  and  6  per  cent.  As  the  carbon  varies,  so  do 
the  other  constituents  of  tar. 

The  distillation  of  different  coke  tars  has  given  the 
following  results : 


i 

2 

3 

4 

5 

6 

7 

8 

Per 

Per 

Per 

Per 

Per 

Per 

Per 

Per 

Cent. 

Cent. 

Cent. 

Cent. 

Cent. 

Cent. 

Cent. 

Cent. 

Water 

2'0 

2-69 

2'T 

trace 

6'60 

3'20 

3  '4° 

37° 

Light  oil 

rj 

1-38 

37 

6'5 

230 

0-80 

4'10 

V20 

Middle  oil  .. 

7-0 

3H6 

9-8 

105 

IO'2O 

5-00 

10-70 

10*50 

Heavy  oil    .. 

14-0 

9'93 

12  -O 

7-6 

8-0 

8-40 

8'60 

7'40 

Anthracene  oil     .  . 

14-0 

2476 

4  '3 

44'3 

26  '70 

22'7O 

ig-OO 

16-80 

Pitch 

000 

56-44 

67-0 

30'5 

49-19 

58-60 

5.5*40 

57-20 

Loss 

i  '5 

I'34 

0-9 

0-4 

0-28 

1-30 

I  -60 

O"2O 

Specific  gravity    ... 

1-16 

1-145-1-191 

1-17 

1-1198 

COAL— COBALT 


125 


COAL  (Continued)— 

According  to  Schniewind,  the  difference  between  gas  tars 
and  coke-furnace  tars  in  distillation  is  given  by  the  follow- 
ing table : 


Fractions. 

Coke-furnace  Tar. 

Gas  Tar. 

Canadian 
Coal. 

Westphalian 
Coal. 

German 
Coal. 

American  Coal. 

Good. 

Bad. 

Light  oil 
Middle  oil 
Heavy  oil 
Anthracene  oil 
Pitch 
Water' 
Loss  ... 

Free  carbon... 
Specific  gravity 

Per  Cent. 
1-26 

1473 
7-07 
21*38 
53'03 
152 
I  '01 

Per  Cent. 
6'55 
10-54 
7  '62 
30-55 
44  '35 
trace 
0-39 

Per  Cent. 
2'5 
2'5 
25-0 
IO'O 

60-0 

Per  Cent. 
I-65 
10-66 
8-18 
14-05 
61-16 
1-81 
2-41 

Per  Cent. 
6'I4 
5^3 
7'50 
II-7I 
68-25 

i  '37 

8-io 
i  -088 

1-1198 

2  5  'oo 
i'i55 

... 

48-4 
i  '255 

A  process  for  the  purification  of  coal  consists  in  grinding 
it  to  powder,  mixing  with  three  or  four  times  its  weight 
of  water,  and  then  agitating  the  mixture  after  addition  of 
a  small  proportion  of  an  oil  or  tar  distillate.  This  produces 
a  froth,  and  the  particles  of  coal  adhere  to  the  air  bubbles 
forming  a  scum  of  purified  coal  which  can  be  skimmed  off 
whilst  the  heavier  associated  impurities  settle.  One  pound 
of  the  added  reagent  is  stated  to  suffice  for  each  ton  of 
the  coal  mixture.  (See  Colloidal  Fuel  and  Floatation 
Process). 

COAL  GAS— See  Gas. 

COBALT  (Co)  and  its  compounds — Atomic  weight,  59  ;  sp.  gr., 
8-5  ;  melting-point,  1,480°  C.  This  metal  occurs  in  nature 
in  several  combinations  with  arsenic  and  sulphur,  including 
smaltite,  or  speiss  cobalt  (cobalt  arsenide,  CoAs2) ;  cobalt 
glance  (cobalt  sulpharsenide,  CoAsS2) ;  and  cobalt  bloom  or 
erythrite  (a  hydrated  arsenate  of  cobalt,  Co3(AsO4)28H2O). 
A  valuable  deposit  of  cobalt  and  erythrite  has  recently 
been  found  in  Queensland. 

The  metal  is  pinkish-white,  very  hard,  ductile,  tenacious, 
and  strongly  magnetic,  and  can  be  obtained  by  reduction 
of  the  oxide. 

There  are  three  oxides — CoO,  Co2O3,  and  Co3O4 — all  of 
which  can  be  used  as  pigments,  the  monoxide  being  soluble 


126  COBALT— COCCULUS  INDICUS 

COBALT  (Continued)— 

in  acids  forming  the  ordinary  cobaltous  salts,  including 
the  pink  coloured  chloride  (CoCl2),  nitrate,  and  sulphate. 
All  cobalt  compounds  give  a  deep  blue  to  glass  or  to  a  bead 
of  borax  when  melted  together.  (See  Boron.) 

Smalt  is  a  fine  blue  glass  used  as  a  pigment  and  in  the 
ceramic  industries,  and  is  prepared  by  roasting  cobalt  ore 
with  quartz  sand  and  potash,  the  fused  mass  being  sub- 
sequently ground  to  a  fine  degree  beneath  water. 

When  cobaltous  chloride  (CoCl2,6H2O)  (which  finds 
use  as  a  colouring  material)  is  gently  heated  to  120°  C.  it 
loses  its  pink  colour  and  becomes  blue  by  the  loss  of  its 
water  of  crystallization—  hence  the  employment  of  the  pink 
compound  in  preparing  sympathetic  inks,  the  faintly  written 
pink  words  becoming  visibly  blue  upon  warming  of  the 
paper  on  which  they  are  written. 

Cobaltous  Nitrate  (Co(NO3)26H2O)  is  soluble  in  water 
and  is  also  used  in  preparing  sympathetic  inks. 

Cobaltous  Sulphate  (CoSO4)  (and  hydrated  CoSO47H2O) 
is  soluble  in  water  and  used  in  ceramics,  whilst  combina- 
tions known  as  cobaltous  oleate  (Co(C18H33O2)2),  linoleate 
(Co(C18H3102)2),  and  resinate  (Co(C44H62O4)2)  are  employed 
as  varnish  driers. 

Cobaltous  Acetate  (Co(C2H3O2)24H2O)  is  a  reddish, 
crystalline  salt  of  deliquescent  nature,  soluble  in  water, 
and  is  used  in  the  preparation  of  sympathetic  inks. 

Cobaltamines — A  number  of  ammoniacal  cobalt  com- 
pounds, of  both  cobaltous  and  cobaltic  character. 

COBALTINE — A  mineral  compound  sulphide  and  arsenide  of 
cobalt  (CoS2  +  CoAs). 

COCA — The  dried  leaves  of  Erythroxylon  coca.  (See  also  Waxes.) 

COCAINE  (C17H21NO4)— A  colourless,  crystalline  alkaloid 
constituting;  the  active  constituent  of  the  coca  leaf  (Ery- 
throxylon coca),  which  can  also  be  prepared  synthetically. 
It  is  used  for  deadening  pain,  and  a  hydrochloride  is  used  in 
ophthalmic  operations. 

COCCULUS  INDICUS— The  fruit  of  a  climbing  shrub  Anamirta 
paniculata)  and  other  allied  varieties  which  grow  on  the 
coasts  of  Malabar  and  in  Ceylon,  etc.  It  contains  about 
-fa  of  its  weight  of  a  bitter  principle  named  picrotoxin 


COCCULUS  INDICUS—«COFECTANT"  127 

COCCULUS  INDICUS  (Continued)— 

(C30H34O13),  which  is  a  strong  narcotic  poison.  It  is 
occasionally  employed  in  the  form  of  an  ointment  for 
destroying pediculi.  Associated  with  the  picrotoxin  is  another 
substance  named  anamirtin  (C19H24O10),  or  cocculin 
(C19H26O12),  which  can  be  obtained  in  white,  crystalline 
needles. 

COCHINEAL — A  reddish  colouring  matter,  consisting  of  car- 
minic  acid,  is  obtained  from  insects  of  the  genus  Coccus, 
which  live  on  various  plants  (Opuntia)  indigenous  in  Mexico, 
but  which  are  also  cultivated  in  many  hot  countries,  in- 
cludingb-the  West  Indies,  Teneriffe,  Madeira,  Algeria,  and 
Java.  The  female  insects  only  are  collected,  and  after 
killing  by  drying  or  heating  they  are  digested  in  hot  water. 
In  the  dry  state,  cochineal  is  an  inodorous,  dark  red, 
granular  material,  which  grinds  to  a  fine  deep  red  colour. 
Boiled  with  water  it  yields  a  dark  red  liquid,  which  can  be 
changed  to  other  colours  by  addition  of  various  chemicals. 
It  is  used  as  a  colouring  for  foods  and  medicines,  also  in 
the  preparation  of  carmine  and  carmine  "  lakes,"  and  for 
dyeing  wool  and  silk  scarlet.  (See  Carmine.) 

COCKLE-BURR  OIL — A  new  seed  drying-oil,  obtained  by  cold 
pressure  from  the  kernels  of  Xanthium  echinatum.  It  is  a 
light,  sparkling  oil  of  pleasant  odour  and  nutty  flavour, 
with  a  sp.  gr.  of  0-9251  at  15-5°  C.,  an  iodine  value  of 
140-8,  and  a  saponification  value  of  190-2. 

COCOA-BUTTER— See  Cacao. 

COCOA-NUT  OIL — A  natural,  semi-solid,  edible,  fatty  oil 
(sp.  gr.  0*9115),  extracted  by  pressure  from  the  kernels  of 
cocoa-nuts,  and  much  used  in  making  soap  and  margarine. 
It  is  very  similar  in  composition  to  palm-nut  oil,  and  is,  to 
some  extent,  obtained  from  the  same  trees.  It  is  soluble 
in  alcohol,  ether,  and  carbon  disulphide,  has  a  saponification 
value  250  to  258,  iodine  value  8-9,  and  melts  at  20°  to  28°  C. 
(See  Copra.) 

CODEINE  (C18H21NOS) — A  colourless,  crystalline,  poisonous 
organic  base,  obtained  from  opium  and  allied  chemically 
to  morphine,  which  melts  at  264°  C.  It  is  soluble  in  water, 
and  is  contained  in  the  mother-liquor  from  which  the 
morphine  has  been  previously  crystallized  out. 

COD-LIVER  OIL— See  Fish  Oils. 

"  COFECTANT "— A  proprietary  phenoloid  disinfectant  pre- 
pared in  a  form  miscible  with  water. 


128  COFFEE— COLCHICUM  AUTUMN  ALE 

COFFEE — The  beans  are  the  seed  of  Caffea  arabica,  belonging 
to  the  rubiaceous  order,  indigenous  in  Southern  Abyssinia, 
but  cultivated  largely  in  West  Indies,  Brazil,  India,  Java, 
Ceylon,  and  elsewhere.  The  beans  are  separated  from 
their  soft  covering  pods  before  they  are  exported.  They 
contain  a  certain  quantity  of  an  essential  oil,  but  caffeine 
(C8H10N4O2)  is  the  active  principle,  and  is  present  to  the 
extent  of  from  0*2  to  0*8  per  cent.  The  beans  lose  about 
half  their  weight  by  washing,  and  about  10  per  cent,  of 
the  roasted  product  passes  into  solution  by  the  process  of 
making  drinking  coffee,  which  acts  as  a  stimulant^  It  is 
the  roasting  that  develops  the  fragrant  odour  associated 
with  coffee,  of  which  there  are  many  varieties'one  of  the 
best  of  which  is  the  Mocha  coffee  that  comes  from  Yemen, 
in  Arabia.  Substitutes  used  as  adulterants  for  coffee 
include  chicory,  caramel,  roasted  cereals,  dandelion-root, 
and  figs.  (See  Caffeine.) 

COHERE — To  cling  or  stick  together. 

COHESION — The  power  or  force  by  which  particles  of  homo- 
geneous substances  are  held  together. 

COHUNE  OIL — Extracted  from  the  kernels  of  the  cohune  palm 
(Attelea  cohune),  which  grows  in  the  British  Honduras, 
Guatemala,  and  Mexico.  It  is  a  yellowish,  semi-liquid  fat, 
which  melts  at  18°  to  20°  C.,  has  a  sp.  gr.  0*868,  saponifica- 
tion  value  252,  and  iodine  value  u  to  13.7.  It  is  soluble  in 
ether  and  benzol,  and  is  used  in  candle  and  soap  making, 
also  for  cooking  purposes. 

COINAGE— See  Gold,  Nickel,  and  Silver. 

COIR — The  outer  coating  or  fibres  of  the  cocoa-nut  used  for 
making  matting  and  brushes,  small  cables  and  rigging. 

COKE— See  Coal. 

COKE-OVENS— See  Coal. 

COLCHICINE  (C^H^NOg)— A  yellow,  crystalline  body,  soluble 
in  water,  alcohol,  and  ether,  of  poisonous  character,  ex- 
tracted from  Colchicum  autumnale. 

COLCHICUM  AUTUMNALE — or  autumnal  crocus — is  a  plant 
which  grows  wild  in  many  parts  of  England,  and  the  root, 
bulb,  and  seeds  are  used  in  pharmacy  for  the  preparation 
of  remedies  against  gout  and  rheumatism.  Colchicum  is  a 
medicine  which  acts  very  powerfully  upon  the  liver  and 
bowels,  and  must  be  used  with  care.  It  contains,  amongst 
Other  ingredients,  about  0*2  per  cent,  of  colchicine. 


COLCOTHAR— COLLOID  129 

COLCOTHAR— A  crude  red  oxide  of  iron  obtained  by  roasting 
green  copperas  (ferrous  sulphate). 

COLEMANITE  (or  BORATE  SPAR)  (Ca2B6On)— A  mineral 
source  of  borax,  found  in  the  United  States,  etc. 

COLLODION — A  solution  of  cellulose  tetranitrate,  or  nitrated 
cellulose,  in  ether  and  alcohol,  largely  used  in  photography, 
as  a  coating  for  various  materials,  as  in  the  making  of 
balloons,  and  in  medicine.  For  general  use  as  for  cuts  it 
may  be  prepared  by  dissolving  40  grains  of  gun-cotton  in 
a  mixture  of  3  oz.  of  ether  and  i  oz.  of  rectified  spirit. 
The  solvent,  being  very  volatile,  leaves  the  dissolved  sub- 
stance as  a  covering  over  the  surfaces  to  be  protected. 

COLLOID — This  term  is  ordinarily  used  to  distinguish  jelly-like 
substances  from  definitely  crystalline  ones  and  includes  the 
living  parts  of  animals  and  plants,  such  as  albumin,  casein, 
cellulose,  and  starch,  which  exhibit  no  evidence  of  internal 
structural  regularity.  While,  however,  the  physical  states 
of  crystalloids  and  colloids  appear  widely  different,  it  has 
been  alleged  that  there  is  some  proof  of  crystallinity  in 
colloids,  and  in  any  case  it  is  certain  that  many  substances 
can  be  prepared  both  ini  crystalline  and  colloid  ("gel") 
form,  so  that  the  difference  is  one  rather  of  degree  than 
essential. 

The  colloidal  form,  then,  is  a  state  or  phase  of  matter,  and 
the  greater  the  complexity  of  a  substance  the  greater  is  the 
probability  of  its  being  in  colloid  form.  One  of  the  most 
complex  colloid  bodies  is  brain-matter  as  a  whole,  and 
although  it  does  not  consist  of  one  homogeneous  com- 
pound the  number  involved  is  relatively  small,  although 
by  acts  of  hydrolysis  it  is  easily  broken  down  into  a  larger 
number  of  still  very  complex  bodies.  It  has  been  compared 
to  a  septum,  on  the  one  side  of  which  is  arterial  blood  and 
cerebro-spinal  fluid  of  the  ventricles,  while  on  the  other  side 
is  cerebro-spinal  fluid  of  the  arachnoidal  space  and  venous 
blood.  To  a  large  extent  it  can  be  washed  free  of  excretory 
and  associated  matters  after  removal  from  the  living  body, 
by  means  of  water,  but  the  alcohol  which  is  ordinarily  used 
to  extract  the  water  of  colloidation  is  necessarily  destructive 
of  its  homogeneity,  setting  free  thereby  the  next  larger 
molecular  groupings  which  were  previously  held  together. 
In  brief,  strong  alcohol  acts  as  a  dehydrating  and  destructive 
agent. 

Colloid  chemistry  has  been  recently  defined  by  Professor 
W.  C.  McC,  Lewis  as  "  the  science  which  deals  with  the 

9 


130  COLLOID 

COLLOID  (Continued)— 

phenomena  occurring  at  the  interfaces  which  separate  two 
contiguous  phases,  such  interfaces  being  very  large  in 
extent  relatively  to  the  actual  masses  of  the  phases  them- 
selves." 

It  is  obvious  that  this  branch  of  chemistry  presents 
infinitely  greater  problems  for  solution  compared  with 
others,  particularly  those  dealing  with  crystalline  sub- 
stances, and  it  is  of  great  importance  in  many  industries  in 
which  colloidal  bodies  are  dealt  with,  such  as  tanning, 
wood-pulp  and  paper  making,  dyeing  of  textiles,  the  soap, 
paint,  and  varnish  trades,  etc. 

Among  inorganic  substances,  silicic  acid  and  cuprous 
oxide  may  be  obtained  in  colloidal  form,  also  a  number  of 
metals  as  obtained  by  reduction  of  their  salts.  Sulphur 
affords  another  striking  instance,  being  obtainable  in  a 
bright  yellow  labile  state  from  its  first  melting-point  up  to 
1 60°  C.,  again  becoming  viscid  on  raising  the  temperature, 
whilst  upon  cooling  to  100°  C.  it  takes  a  distinctly  new 
phase,  solidifying  in  insoluble  form. 

Styrene  (C8H8)  is  a  hydrocarbon  which  polymerizes  spon- 
taneously upon  standing,  into  a  jelly-like  mass,  and  there 
are  a  number  of  so-named  metallic  organosols  and  metallic 
colloids  known  in  various  dispersion  media. 

Graham,  who  first  of  all  studied  colloidal  chemistry  in  any 
fulness,  was  aware  that  different  dispersion  media  could  be 
employed  to  displace  each  other  without  destroying  the 
colloidal  state,  replacing  for  example  the  water  of  silicic 
acid  "  gel "  with  alcohol,  sulphuric  acid,  etc. 

A  colloidal  solution  is  really  a  two-phase  system  consisting 
of  a  fluid  medium  and  suspended  particles,  thus  providing  a 
very  large  surface  of  contact  between  the  colloid  body  and 
its  medium.  When,  therefore,  a  substance  is  introduced 
into  such  a  system  it  is  frequently  found  concentrated  at 
the  surface  of  one  of  the  phases,  thus  presenting  the  phe- 
nomenon known  as  adsorption.  Many  dyes  give  colloidal 
solutions,  the  dyeing  depending  upon  the  adsorption  of 
them  by  the  fibres,  and  the  same  state  of  things  is  realized 
in  the  behaviour  of  hides  to  tannin  solutions. 

The  tints  of  coloured  glasses  are  frequently  due  to  the 
metals  being  in  a  colloidal  state,  as  for  example  in  "  gold 
ruby  glass." 

Most  substances  in  colloidal  solution  assume  an  electric 
charge  towards  their  dispersion  medium,  and  when  sus- 
pended in  water  can  often  be  coagulated  or  precipitated  by 
physical  agencies  or  by  the  addition  of  certain  chemicals  as 


COLLOID  I3i 

COLLOID  (Continued)— 

exemplified  by  the  use  of  calcium  hydrate  and  aluminium 
sulphate  to  effect  the  precipitation  of  organic  matters  con- 
tained in  sewage  ^sludge. 

It  is  well  known  that  pollen  grains  suspended  in  water 
are  in  constant  motion,  and  this  so-called  "  Brownian " 
movement  and  other  similar  oscillatory  movements  observ- 
able in  many  colloidal  mixtures  are  due  to  sources  of  energy 
within  the  fluids  of  a  kinetic  character — that  is,  collisions 
between  the  molecules  of  the  dispersion  media. 

Among  the  terms  commonly  used  in  association  with 
colloidal  chemistry  are  those  of  "gel,"  "sol,"  "  hydrosol," 
"  suspenoids,"  "  emulsoids,"  and  "  peptisation." 

"Gel"  is  the  name  given  to  any  gelatinous  mass  produced 
by  slow  change,  physical  action,  or  by  addition  of  saline 
substances  to  the  solution  of  a  colloid  body.  A  silica  gel, 
for  example,  can  be  prepared  by  the  addition  of  an  acid 
such  as  hydrochloric  acid  to  a  solution  of  sodium  silicate  in 
such  proportions  as  to  set  free  all  the  silica,  when  upon 
standing  the  "  gel  "  forms.  This,  when  washed,  dried,  and 
finely  pulverized,  can  be  used  as  a  substitute  for  charcoal 
for  adsorptive  purposes. 

"  Sol "  is  the  name  given  to  a  colloidal  solution  from 
which  a  "gel"  is  obtainable — in  fact,  a  "  sol "  becomes  a 
"  gel "  when  its  degree  of  dispersion  is  so  decreased  that  it 
passes  beyond  the  lower  limits  characteristic  of  the  colloidal 
solution. 

Many  substances  may  be  prepared  in  the  form  of  colloidal 
solution,  as,  for  example,  the  hydroxides  of  aluminium,  iron, 
chromium,  and  tungstic  acid,  all  of  which  can  be  coagulated 
by  addition  of  an  electrolyte  or  certain  soluble  salts. 

"  Sols  "  of  gold,  silver,  and  platinum  can  also  be  obtained. 

The  majority  of  colloidal  solutions  exhibit  opalescence 
when  a  powerful  beam  of  light  is  passed  through  them  and 
the  individual  particles  in  suspension  can  be  seen  by  the 
microscope,  although  in  some  cases  they  will  pass  through 
the  finest-filter  paper,  and  cannot  be  discerned  even  with 
the  ultra-microscope,  so  that  there  is  no  hard-and-fast  line 
between  colloidal  and  crystalloid  solutions,  the  particles 
where  discernible  being  always  in  motion  essentially  the 
same  as  the  "  Brownian  "  movement. 

"  Hydrosols  "  are  colloids  having  water  as  the  dispersion 
medium  and  exhibiting  a  gradual  transition  in  properties 
from  coarse  suspensions  through  "  sols  "  to  true  solutions 
as  ordinarily  understood. 

"  Suspenoids  "  are  "  sols  "  in  which  the  disperse  phase  is 


132  COLLOID— COLOCYNTH 

COLLOID  (Continued)— 

solid,  and  "emulsoids"  are  "  sols  "  in  which  the  disperse 
phase  is  liquid. 

"  Peptisation"  implies  means  of  preventing  sedimentation 
of  precipitates,  thus  preserving  them  in  a  colloidal  state. 
Thus  the  hydroxides  of  iron,  nickel,  thorium,  mercury,  and 
cobalt  are  all  "  peptised  "  by  adding  a  caustic  alkali  to  the 
solutions  of  salts  of  those  metals  in  the  presence  of  glycerine 
or  sugar. 

The  major  part  of  the  hydroxides  of  aluminium,  chromium, 
lead,  mercury,  and  copper,  when  dissolved  in  potassium  or 
sodium  hydroxide,  exist  in  a  colloidal  state.  In  an  electric 
field,  ferric  hydrate  in  colloidal  solution  is  attracted  by  the 
negative  pole  and  that  of  arsenious  sulphide  by  the  positive 
pole  when  two  wires  from  a  battery  are  passed  therein, 
so  that  it  is  thought  they  carry  the  opposing  electric  charges 
respectively. 

(See  also  Adsorption,  Dialysis,  Crystals,  Emulsions,  and 
Osmosis.) 

"COLLOIDAL  FUEL"  (Liquid  Fuel)— An  emulsified  mixture 
of  very  finely  divided  coal  and  mineral  oil.  One  such 
recommended  mixture  is  30  per  cent,  coal,  10  per  cent,  coal- 
tar  distillate,  and  60  per  cent,  mineral  oil,  the  properties 
of  which,  such  as  sp.  gr.,  heat  value,  and  viscosity,  are 
proportional  to  the  respective  amounts  of  the  ingredients. 
Where  "  slack  "  or  powdered  anthracite  coal,  coke,  or  pitch 
is  available  and  cheap,  such  mixtures  may  be  usefully 
employed  in  place  of  ordinary  coal.  Powdered  dry  coal 
is  very  mobile,  and  when  suspended  in  fuel  oil  it  can  be 
passed  through  an  ordinary  fuel  oil  burner,  but  it  is  apt 
to  separate  on  standing,  to  overcome  which  characteristic 
recourse  is  had  to  the  use  of  a  so-called  "  fixateur  " — that 
is,  a  substance  which  keeps  the  coal  dust  in  more  or  less 
permanent  suspension.  To  obtain  the  best  results,  the 
carbonaceous  matter  should  be  ground  so  fine  that  97  per 
cent,  will  pass  through  a  loo-mesh  screen,  and  at  least 
85  per  cent,  through  a  2oo-mesh  screen.  The  flash-points 
of  most  such  fuels  vary  from  250°  to  280°  F. 

COLOCYNTH — The  fruit  of  a  creeping  plant  known  as  the 
"  bitter  apple,"  growing  chiefly  on  the  shores  of  the 
Mediterranean.  An  extract  made  from  the  pulp  is  largely 
used  in  medicine  as  a  purgative — either  alone  or  in  com- 
bination with  other  drugs.  It  contains  as  its  active 
principle  a  very  bitter  substance  named  "  colocynthin," 
which  appears  to  have  the  character  of  a  glucoside. 


COLOPHONY— CONCRETE  133 

COLOPHONY— See  Resins. 

COLORIMETER — An  instrument  for  making  a  comparison 
between  the  colours  or  depth  of  tint  of  a  column  of  liquid 
with  that  of  a  prepared  standard  solution. 

COLOUR— See  Light. 

COLOURS — In  addition  to  cochineal,  indigo,  madder,  log- 
wood, and  safflower,  the  colouring  principles  of  the  damask 
rose,  the  poppy,  turmeric,  litmus,  and  red  cabbage  are  still 
employed,  but  the  synthetically  prepared  coal-tar  colours 
have  superseded  the  natural  vegetable  colours  to  a  very 
•  large  extent.  (See  Dyes  and  Plant  Colouring  Matters.) 

COLUMBITE  (Tantalite)— See  Columbium. 

COLUMBIUM  (or  NIOBIUM)  (Cb)  —  Atomic  weight,  93-5; 
sp.  gr.,  7;  melting-point  about  1,950°  C.  A  rare  metal  of 
grey  colour  and  bright  lustre,  found  in  nature  in  association 
with  tantalum  in  a  number  of  minerals,  occurring  in  Sweden 
and  some  of  the  United  States  of  America,  including  columbite 
and  tantalite.  It  is  not  attacked  by  acids,  excepting  a 
mixture  of  nitric  and  hydrofluoric  acids ;  is  hard  as 
wrought-iron,  and  combines  with  hydrogen  and  nitrogen. 

Three  oxides  are  known — viz.,  CbO,  CbO2,  and  Cb2O3 ; 
and  two  chlorides — viz.,  CbCl3  and  CbCl5.  The  metal 
itself  is  obtained  by  heating  the  trichloride  (CbCl3)  in  a 
current  of  hydrogen  gas. 

COLZA  OIL— See  Rape  Seed  Oil. 
COMBINING  PROPORTIONS— See  Equivalents. 
COMBUSTION — See  Air ;  also  Organic  Analyses. 
COMPONENT — A  constituent  or  part  of  a  substance. 
COMPOUNDS— See  Chemical  Compounds. 

COMPRESSED— Pressed  or  squeezed  together  to  occupy  less 
space. 

CONCAVE — A  gentle  hollowing  in  from  the  sides  to  the  centre. 
CONCENTRATION — Strengthening  a  solution,  as  for  example 

by  evaporation,  or  by  dissolving  more  of  the  substance 

in  it. 

CONCRETE — Several  varieties  of  concrete  are  made,  but  the 
constituents  are  always  cement,  a  fine  aggregate  (usually 
sand)  and  a  coarse  one  (usually  pebbles  or  broken  stones 
or  breeze),  the  purpose  of  the  fine  material  being  to  save 
cement  by  filling  up  more  closely  the  pore  spaces. 

Reinforced  concrete  is  made  by  embedding  steel  or  other 
material  to  increase  the  strength. 


134  CONCRETE— CONVEX 

CONCRETE  (Continued)— 

Recently,  blast-furnace  slag  has  been  employed  as  a  sub- 
stitute for  gravel  and  sand  in  concrete,  and  experience  in 
Germany  appears  to  indicate  that  the  resulting  product 
is  stronger  than  that  made  by  using  Rhine  sand.  (See 
Cement.) 

CONDENSATION — Apart  from  its  ordinary  meaning,  this  term 
has  a  special  interpretation  in  organic  chemistry — viz.,  to 
indicate  the  formation  of  a  new  body  by  interaction,  attended 
generally  with  the  separation  of  either  water,  alcohol,  am- 
monia, or  hydrochloric  acid,  etc.  Acetic  anhydride  is,  for 
example,  a  condensed  compound  derived  from  acetic  acid  by 
the  elimination  of  water  : 

2C2H402-H2O  =  C4H6O3. 
(See  also  Distillation.) 

"  CONDY'S  FLUID  " — A  proprietary  liquid  disinfectant  contain- 
ing sodium  permanganate. 

CONGELATION— The  solidification  of  liquids  by  cooling  or 
freezing. 

CONGO-BED — An  artificial  red  dye  for  cotton  goods. 

CONIFERIN  (C16H22O8,2H2O)— A  compound  of  glucoside 
character  contained  in  the  sap  of  the  cambium  in  the 
Conifera,  from  which  vanillin  can  be  obtained. 

CONIINE— See  Hemlock. 

CONNECTORS  include  varieties  of  india-rubber  tubing,  as 
used  for  connecting  glass  tubes  of  approximately  the  same 
diameter  and  lamps  and  gas-burners  with  the  taps  of  the 
supply-pipe,  etc. 

In  some  cases — as,  for  example,  when  the  chemicals 
employed  are  known  to  have  a  destructive  action  on  rubber 
— a  glass  connector  is  employed,  being  another  short  length 
of  tube  somewhat  larger  in  diameter  than  the  other  two 
glass  tubes  to  be  connected,  so  that  the  ends  of  the  last 
named  may  just  enter  the  larger  tube,  the  joints  being  made 
tight  by  means  of  melted  paraffin  wax. 

CONSTANTS  (Chemical)— Determined  values  of  chemical 
substances,  such  as  atomic  weights,  vapour  densities, 
specific  gravities,  melting-  and  boiling-points,  the  saponifica- 
tion  and  iodine  values  of  fats  and  oils,  etc. 

CONSTITUENT — An  ingredient  of  a  substance. 

CONTACT  ACTION— See  Catalytic. 

CONVEX — A  gentle  swelling  out  from  the  sides  to  the  centre. 


CON  VOL  VULIN— COPPER  135 

CONVOLVULIN — A  glucosoidal  resin  contained  in  the  tuberose 
of  the  Convolvulus  schiedanus  (Zucc.),  having  purgative  pro- 
perties. 

"  COOPERITE  " — A  new  proprietary  non-ferrous  alloy,  stated  to 
be  very  efficient  for  making  machine-tools,  containing  zir- 
conium, molybdenum,  tungsten,  silicon,  and  aluminium ; 
iron  being  replaced  by  nickel  as  a  basic  constituent  for  tool 
production. 

COPAIBA  OIL — The  volatile  oil  contained  in  balsam  of  copaiba 
to  the  extent  of  some  30  to  60  per  cent.  It  belongs  to  the 
class  of  terpenes ;  is  colourless  or  pale  yellow,  of  aromatic 
odour,  is  soluble  in  alcohol,  ether,  etc.,  and  finds  some  use 
in  medicinal  practice.  Sp.  gr.,  0-885  to  0*918;  refractive 
index,  i'493  to  1*502  ;  optical  rotation  -4°  to  -  35°,  accord- 
ing to  variety. 

COPAL  GUM  or  RESIN  (Cowrie,  Anime)  exudes  naturally  from 
a  number  of  trees,  including  the  Rhus  copallina  of  North 
America,  the  Elaocavpus  copaliferoi  the  East  Indies,  and  the 
Hymencea,  vermcosa  of  Madagascar.  The  Zanzibar  gum  is 
of  both  fossil  and  recent  character.  The  lumps  of  this  hard 
resin,  which  is  used  in  making  high-quality  copal  coach 
varnish,  are  yellowish  in  colour,  hard,  have  a  lustrous 
appearance,  and  easily  fracture.  The  several  varieties 
differ  to  some  extent  in  their  solubilities  in  various  liquids 
such  as  alcohol  and  turpentine  oil,  and  by  exposure  to  the 
air  they  absorb  oxygen  and  become  more  soluble.  The 
solubility  is  also  increased  by  melting  the  copal  at  the 
lowest  possible  temperature.  (See  Varnishes.) 

COPPER  (Cuprum,  Cu) — Atomic  weight,  63-5  ;  sp.  gr.,  8-95 ; 
melting-point,  1,083°  C.  Copper  is  found  in  many  places  in 
the  metallic  state,  and  even  in  large  masses  near  Lake 
Superior  (U.S.A.)  and  in  some  Siberian  mines.  It  also 
occurs  in  nature  in  the  form  of  copper  pyrites,  or  double 
sulphide  of  copper  and  iron  (Cu2S.Fe2S3).  The  Rio  Tinto, 
Mason,  and  Barry  ores  are  of  this  description. 

Copper  ore  is  also  found  in  Australia  in  the  form  of  car- 
bonate, and  as  oxide  and  sulphide  in  Cuba,  while  that  from 
Chile  is  associated  with  a  valuable  proportion  of  silver. 
Azurite  and  malachite  are  native  carbonates  of  copper. 

When  the  oxide  of  copper  is  used  for  production  of  the 
metal,  it  is  smelted  in  a  blast-furnace  with  coal  or  coke,  by 
which  it  is  reduced  as  shown  by  the  equation — 


136  COPPER 

COPPER  (Continued)— 

that  is  to  say,  the  oxygen  of  the  cuprous  oxide  enters  into 
combination  with  the  carbon  of  the  coal  or  coke,  forming 
carbon  monoxide,  and  the  metallic  copper  thus  produced  is 
afterwards  refined  by  other  processes. 

With  other  ores  of  copper  containing  sulphides,  the 
sulphur  content  has  first  of  all  to  be  roasted  off  as  sulphur 
dioxide,  and  consequently  different  processes  are  necessary. 

There  is  a  process  for  the  extraction  of  copper  from  some 
of  its  ores  by  so-called  ammonia  leaching,  in  which  the 
natural  sulphide  ores  are  roasted  into  oxides,  and  then 
treated  with  ammonia  solution,  thus  producing  a  dark  blue 
liquid  which  upon  heating  gives  off  ammonia  vapour  and 
carbon  dioxide  gas,  and  deposits  a  heavy  black  powder  con- 
sisting in  the  main  of  cupric  oxide  (CuO). 

The  copper  "  matte,"  containing  from  40  to  50  per  cent, 
copper,  obtained  by  the  roasting  and  reduction  processes, 
furnishes  the  crude  material  from  which  the  "blister" 
copper  is  subsequently  obtained  by  a  remelting  process, 
and  this  again  is  further  refined  by  an  electrolytic  process 
which  yields  ingots  of  99*9  per  cent,  purity  as  used  for  the 
metal-working  industries. 

The  copper,  which  is  contained  (to  the  extent  of  about 
3  per  cent.)  in  the  burnt  pyrites  used  in  the  alkali  manufacture, 
is  extracted  by  a  wet  process  in  which  the  residual  mass  is 
calcined  with  salt,  which  converts  the  copper  into  the  form 
of  chloride,  after  which  the  fused  mass  is  lixiviated  with 
water  and  the  copper  precipitated  from  the  solution  by 
means  of  scrap-iron  or  by  electrolysis.  The  metal  so 
obtained  in  a  spongy  condition  can  either  be  smelted,  or 
roasted  into  oxide,  and  sometimes  the  oxide  so  prepared  is 
subsequently  dissolved  in  sulphuric  acid  in  order  to  produce 
cupric  sulphate,  which  can  be  crystallized  out  from  the 
solution. 

Most  of  the  copper-smelting  in  this  country  is  carried  out' 
at  Swansea.     The  refining  and  manufacture  of  copper  is 
the  most  important  metal  industry  in  Japan,  the  exported 
quantity  being  worth  about  ^"10,000,000  per  annum. 

Copper  is  one  of  the  most  useful  metals ;  has  a  reddish 
colour,  is  rather  hard  but  flexible,  tenacious,  very  ductile 
and  malleable,  and,  apart  from  its  employment  in  the  form 
of  wire  for  telegraphic  purposes  (on  account  of  its  excel- 
lent conductivity),  is  largely  used  for  making  domestic 
utensils,  coins,  sheathing  of  wooden  ships,  etc.  It  enters 
into  the  composition  of  many  alloys ;  for  example,  with 
various  proportions  of  tin,  it  forms  bronze,  bell-metal, 


COPPER  AND  ITS  COMPOUNDS  137 

COPPER  (Continued)— 

and  gun-metal,  while  brass  is  an  alloy  of  about  2  parts  of 
copper  with  i  part  of  zinc,  and  Muntz  metal  is  an  alloy  of 
3  parts  copper  with  i  part  zinc.  A  new  alloy  of  copper 
and  aluminium  of  golden  colour  named  "Alcobronze"  has 
been  recently  invented,  stated  to  be  stronger,  tougher,  and 
harder  than  any  other  known  bronze  and  capable  of  resist- 
ing the  influence  of  air,  acids,  and  salt  water. 

Copper  Oxides. — There  are  two  oxides  of  copper — viz., 
the  red  cuprous  oxide  (Cu2O),  which  gives  to  glass  a 
beautiful  ruby  colouration ;  and  cupric  oxide  (CuO),  which 
is  black  and  produces  blue  and  green  salts  by  combination 
with  acids.  Cuprous  oxide  occurs  in  a  crystalline  condition 
in  nature  as  red  copper  ore  and  in  the  precipitated  form  is 
useful  as  a  catalytic  agent,  also  in  compounding  anti- 
fouling  compositions  and  paints  for  ships. 

A  solution  of  the  hydrated  cupric  oxide  or  cupric 
hydroxide  (Cu(HO)2)  in  ammonia  is  used  in  the  prepara- 
tion of  "Willesden  paper"  and  artificial  silk,  while  the 
hydroxide  itself  is  used  as  a  pigment.  (See  Cellulose.) 

Copper  Chlorides. — There  are  two  chlorides  of  copper 
corresponding  to  the  two  oxides.  The  cuprous  chloride 
(Cu2CL2)  is  insoluble  in  water,  but  the  cupric  chloride  (CuCl2) 
is  readily  soluble,  giving  a  deep  green  coloured  solution. 

Cupric  Nitrate  is  a  soluble  crystalline  salt  having  the  com- 
position Cu(NO3)2,3H2O. 

Cupric  Sulphate  (CuSO4.5H2O)  is  the  most  important 
salt  of  copper  and  is  formed  when  the  metal  or  its  oxide 
is  dissolved  in  sulphuric  acid.  It  is  soluble  in  water,  and 
when  such  a  solution  is  concentrated  by  heat  and  allowed 
to  cool,  the  sulphate  crystallizes  out  in  fine  blue  crystals 
containing  5  molecules  of  water,  as  shown  by  its  formula. 
It  is  used  as  a  mordant  in  dyeing,  in  the  manufacture  of 
"  Scheele's  green,"  "  Brunswick  green  "  and  other  pigments, 
in  electric  batteries,  and  in  preparing  a  number  of  com- 
pounds used  for  the  destruction  of  low  forms  of  insect  pests 
on  vines  and  other  plants. 

Copper  Sulphides. — There  are  two  sulphides  of  copper 
corresponding  to  the  two  oxides — the  cuprous  sulphide 
(Cu2S),  being  identical  with  the  mineral  known  as  crystal- 
line copper  glance ;  and  cupric  sulphide  (CuS),  which  is 
chemically  identical  with  the  mineral  indigo  copper — and 
both  are  used  as  protective  paints  on  ships. 


I38  COPPER  COMPOUNDS— COPRA 

COPPER  (Continued)— 

Scheele's  Green  (CuHAsO3)  is  an  arsenite  of  copper  of 
bright  green  colour  used  as  a  pigment.  It  is  made  by 
mixing  solutions  of  cupric  sulphate  and  sodium  arsenite,  or 
by  dissolving  arsenious  oxide  (As2O3)  in  potassium  car- 
bonate solution  and  adding  to  it  a  solution  of  copper 
sulphate  in  water.  (See  also  Paris  Green.) 

Brunswick  Green  is  a  pigment  (copper  oxy chloride)  made 
by  moistening  copper  turnings  with  a  solution  of  ammonium 
chloride  (sal  ammoniac),  and  exposure  to  the  air. 

Cupric  Acetate  (Cu(C2H3O2)22H2O)— A  greenish-blue 
crystalline  body,  soluble  in  water  and  alcohol,  which  finds 
employment  as  an  insecticide,  in  ceramics,  and  in  printing 
fabrics. 

Copper  Carbonates. — Two  carbonates  are  known,  one  of 
which  is  identical  in  composition  with  native  malachite 
(CuCO3,Cu(HO)2),  and  another  identical  in  composition 
with  azurite  (2CuCO3,Cu(HO)2),  both  of  which  are  in- 
soluble green  powders  used  as  pigments. 

Cupric  Chlorate  (Cu(ClO3)26H2O) — A  bluish-green,  deli- 
quescent, crystalline  body,  soluble  in  water  (although 
dangerous  in  character,  like  most  chlorates) ;  used  as  a 
mordant. 

Cupric  Cyanide  (Cu(CN)2) — A  green  powder,  insoluble 
in  water,  used  in  metallurgy. 

Cupric  Fluoride  (CuF2.2H2O) — A  blue,  crystalline  salt, 
soluble  in  water  ;  used  in  ceramics  and  enamels. 

Cuprous  Phosphide  (Cu3P2)  is  a  dark  metallic- looking 
powder  used  in  making  phosphor  bronze. 

Cupric  Resinate  (Cu(C20H29O2)2)  is  a  green  compound 
soluble  in  ether  and  oils,  and  used  as  a  metal  paint,  and  in 
in  particular  for  ships'  bottoms. 

The  salts  of  copper  are  poisonous. 

COPPERAS  (Blue) — A  common  name  for  cupric  sulphate. 
COPPERAS  (Green) — A  common  name  for  ferrous  sulphate. 

COPRA — The  dried  edible  part  of  the  common  cocoa-nut,  as 
prepared  for  the  extraction  of  the  white,  wax-like,  semi- 
solid  fat,  of  which  it  contains,  when  dry,  up  to  50  per  cent., 
and  which  is  used  in  the  manufacture  of  soaps,  candles, 
etc.  The  sp.  gr.  of  this  semi-solid  fat  is  from  0-910  to 
0-926,  and  its  melting-point  23°  to  27°  C.  Copra-meal  is 
stated  to  be  rich  in  the  ammo-acids  necessary  for  the 


COPRA— CORN  OIL  139 

COPE  A  (Continued)— 

maintenance  of  growth,  and  when  mixed  with  green  leaves 
furnishes  a  fairly  perfect  food  for  pigs. 

COPROLITES— Imported  phosphatic  deposits  in  the  nature  of 
extinct  animal  excrements  found  in  certain  geological 
formations,  particularly  in  the  lias.  They  consist  chiefly 
of  calcium  phosphate  and  carbonate,  the  phosphate  amount- 
ing in  some  cases  to  as  much  as  from  80  to  90  per  cent., 
and  on  account  of  their  phosphatic  character  they  are 
very  valuable  fertilizers.  During  the  war,  the  deposits  in 
Cambridgeshire  were  mined,  but  at  a  cost  exceeding  the 
pre-war  cost  of  the  imported  products.  Phosphate  deposits 
are  found  in  the  Society  Islands  as  soil,  also  in  Cura9ao 
and  in  Tunis,  the  former  running  about  80  per  cent,  phos- 
phate. (See  Guano.) 

CORAL— See  Calcium. 
CORDITE— See  Explosives. 

CORIANDER  OIL — A  volatile  essential  oil  of  mixed  character 
and  aromatic  taste,  obtained  by  distillation  with  water  of 
the  seeds  or  fruit  of  the  Coriandrum  sativum.  The  fruit 
contains  about  0*37  per  cent,  of  the  oil,  which  in  the  dilute 
state  has  the  smell  of  orange  flowers,  is  used  for  flavouring, 
and  acts  as  a  pleasant  but  powerful  carminative.  It  is  soluble 
in  alcohol  and  ether,  has  a  sp.  gr.  0*860  to  0*895,  optical 
rotation  +9°  to  + 11°,  and  refractive  index  1*464  to  1*4775. 

CORK  is  the  outer  bark  of  the  Quercus  suber  tree,  which  grows 
in  the  southern  part  of  Europe,  the  north  of  Africa,  and  in 
the  East,  and  consists  of  a  modified  form  of  cellulose. 
When  oxidized  with  nitric  acid  it  yields,  amongst  other 
products,  oxalic  acid.  Its  approximate  sp.  gr.  is  0*25. 

CORKS  are  made  from  the  outer  bark  of  the  cork-tree. 

CORK-BORERS  are  hollow  metallic  tubes  of  brass  or  steel, 
with  sharpened  ends  for  boring  holes  through  corks. 

CORK-SQUEEZER — A  mechanical  contrivance  for  squeezing 
corks,  as  found  necessary  to  adjust  their  fitting  well  as 
stoppers. 

CORNELIANS— Beautiful  variegated  stones  of  the  nature  of 
chalcedony  found  in  India. 

CORN  OIL  (Maize  Oil) — Expressed  from  Indian  corn,  is  pale 
yellow,  has  a  sp.  gr.  0-92  to  0-925,  and  is  soluble  in  ether, 
chloroform,  and  benzol.  It  is  used  as  a  foodstuff,  in 
making  soaps  and  lubricants,  and  as  a  substitute  for  Ghee 
in  certain  Eastern  areas. 


140  CORROSIVE  SUBLIMATE— COUMARIN 

CORROSIVE  SUBLIMATE— Mercuric  chloride  (HgCl2).  (See 
Mercury.) 

CORUNDUM— See  Aluminium. 

COTARNINE  (C12H15NO4)— A  primrose-coloured,  crystalline 
base  obtained  by  oxidizing  narcotine.  It  is  soluble  in 
water  and  alcohol,  and  in  common  with  the  hydrochloride 
(stypicinin),  is  used  in  medicine. 

COTTON-SEED  OIL  —The  oil  is  expressed  with  the  aid  of  heat 
from  cotton-seeds  (Gossypium  herbaceum),  and  largely  used 
in  making  margarine,  as  a  leather  dressing,  lubricant,  and 
in  soap-making.  Large  amounts  of  cotton-seed  come  from 
Korea  and  North  China,  which  supply  the  Japanese  mills. 
Supplies  come  also  from  Egypt,  but  probably  the  largest 
amount  is  produced  in  the  United  States.  Its  sp.  gr.  is 
0-922  to  0*927,  saponification  value  193  to  195,  and  iodine 
value  1 08  to  1 1 6.  The  hair  of  the  seeds  is  used  for  making 
cotton,  which  consists  of  almost  pure  cellulose.  Cotton- 
seed oil  is  refined  by  steam-heating  it  with  5  per  cent,  of  a  16° 
Baume  caustic  soda  lye  and  settling,  93  per  cent,  of  refined 
oil  being  thus  obtained.  From  a  recent  analysis  of  Sea  Island 
cotton-seed  oil,  the  authors  concluded  that  it  consisted  of 
glycerides  of  the  following  acids  :  myristic,  0-3 ;  palmitic, 
20  ;  stearic,  2  ;  arachidic,  0*6  ;  oleic,  35-2  ;  and  linolic,  41*7 
per  cent.  Upon  chilling,  it  deposits  so-called  "  cotton 
stearine,"  composed  chiefly  of  stearine  mixed  with  some 
other  glycerides,  and  when  the  stearine  has  been  removed 
the  oil  is  known  as  "  winter  oil,"  as  it  does  not  readily 
solidify  in  cold  weather. 

COTTRELL  PRECIPITATING  PLANT— An  electrical  arrange- 
ment for  condensing  mists  and  recovering  valuable  con- 
stituents of  waste  gases.  A  metallic  plate  is  connected 
with  one  terminal  of  high  voltage,  and  the  other  carries  a 
needle  point  placed  opposite  the  plate,  so  that  the  suspended 
liquid  or  solid  particles  contained  in  the  gases  passing 
through  the  gap  between  the  two,  becomes  charged  with 
electricity  and  condensed,  or  are  deposited.  This  plant  can 
be  usefully  applied  to  cause  the  condensation  of  the  mist- 
like  fumes  generated  in  the  concentration  of  sulphuric  acid, 
the  recovery  of  lead  from  the  waste  gases  of  lead  furnaces, 
deposition  of  the  suspended  dust  in  the  waste  gases  from 
cement  works  and  that  of  arsenious  oxide  from  the  fumes 
yielded  by  roasting  arsenical  ores,  etc. 

COUMARIN  (C9H6O2)— The  aromatic  principle  of  woodruff 
(Asperula  odorata),  sweet-scented  vernal  grass,  etc.  It  is 


COUMARIN-  CREAM  OF  TARTAR  141 

COUMARIN  (Continued)— 

also  found  in  the  Tonka  bean  (the  fruit  of  Coumamma 
odorata),  in  the  form  of  small  colourless  crystals  between 
the  seed  coating  and  the  kernel.  There  is  reason  for 
thinking  it  results  from  the  decomposition  of  a  glucoside. 
Being  soluble  in  alcohol  it  can  be  easily  extracted  from 
Tonka  beans.  In  a  pure  state  it  is  a  colourless,  crystalline 
substance  readily  soluble  in  alcohol,  ether,  and  hot  water, 
has  an  agreeable  aromatic  odour,  and  its  vapour  is  said  to 
act  very  strongly  on  the  brain.  It  can  be  prepared 
synthetically  from  salicylic  aldehyde. 

COUMARONE  RESIN  (C6H4.CH.O.CH)— A  resinous  body  of 
varying  melting-point,  soluble  in  petroleum,  turpentine, 
acetone,  and  carbon  disulphide,  obtained  by  the  polymeri- 
zation of  coumarone  and  indene  contained  in  certain 
aromatic  naphthas,  by  means  of  heat  or  the  action  of 
mineral  acids. 

Paracoumarone  resin,  formed  by  polymerization,  is  made 
in  the  United  States  in  large  quantities.  It  is  gummy 
to  hard  in  character,  and  is  found  quite  suitable  for  re- 
placing ester  gum,  or  even  kauri-gum,  and  others  in  varnish- 
making  and  rubber  substitutes.  It  is  made  by  treatment 
of  the  distillate  fraction  of  solvent  naphtha  between  160° 
and  200°  C.  with  either  strong  sulphuric  acid  or  aluminium 
chloride,  or  by  simply  heating  under  pressure  and  subsequent 
separation  from  the  polymerizing  agent,  when  it  sets  to  a 
solid  resin-like  mass  of  sp.  gr.  1*05  to  1*10  and  is  soluble  in 
petroleum,  ether,  carbon  disulphide,  etc. 

COWRIE— See  Kauri. 
COW-TREE  WAX -See  Waxes. 

CRACKING — Destructive  distillation  of  solid  and  liquid  bodies. 
(See  Distillation.) 

CREAM  OF  TARTAR — A  white,  crystalline,  acid  tartrate  of 
potassium  (C4H5O6K),  soluble  in  water,  used  both  in 
medicine  and  in  the  dyeing  industry.  It  is  often  deposited 
from  wines  kept  in  casks  (see  Tartar).  In  admixture  with 
varying  proportions  of  saltpetre,  it  furnishes  the  black  and 
white  fluxes  which  are  used  in  metallurgical  and  assaying 
operations,  and  when  pounded  and  mixed  with  chalk  and 
alum  it  makes  an  excellent  powder  for  polishing  articles  of 
silver. 


142  ORE  A  TINE—CRESOL 

CREATINE  (C4HLN3O2)— A  crystalline  body  contained  in  the 
juice  of  animal  muscles  (flesh),  soluble  in  hot  water,  and 
which  combines  with  hydrochloric  acid  to  form  a  well-defined 
compound,  C4H9N3O2,HC1.  It  is  accompanied  by  another 
substance,  named  creatinine  (C4H7N3O) — an  invariable 
constituent  of  urine. 

Creatine  appears  to  become  changed  in  the  blood  into 
urea  and  creatinine. 

"CREOCIDE" — A  proprietary  fluid  disinfectant,  prepared 
from  certain  cresotic  principles. 

CREOSOL  (C8H1?O2)— -A  liquid  derivative  of  catechol  resem- 
bling guaiacol,  boiling  at  220°  C.,  and  forming  the  chief 
constituent  of  beechwood  tar. 

CREOSOTE — See  Beechwood  Creosote  and  Coal. 

CREOSOTE  (Wood)— Creosote  as  obtained  by  the  distillation 
of  wood  is  quite  distinct  from  coal-tar  creosote,  although 
both  contain  certain  ingredients  in  common.  When  refined 
it  is  a  colourless,  oily  liquid  of  complex  composition, 
containing  phenol  and  cresol,  having  a  pungent,  penetrating 
odour,  and  it  is  to  its  active  principles  that  wood-vinegar, 
tar-water,  soot,  and  smoke  owe  their  preservative  and 
antiseptic  value.  It  is  probably  more  definitely  allied 
to  blast-furnace  creosote  in  chemical  nature  than  to  coal-tar 
creosote. 

CREOSOTE  CARBONATE  (also  known  under  the  commercial 
name  of  "creosotal") — A  clear,  colourless,  or  amber- 
coloured,  viscid  liquid  consisting  of  an  indefinite  mixture, 
made  by  conducting  a  stream  of  phosgene  gas  (carbonyl 
chloride,  COC12)  into  a  solution  of  creosote  in  sodium 
hydrate.  The  oily  liquid  thus  produced  in  a  separated 
form,  is  first  washed  with  a  weak  alkali  and  then  with 
water.  It  contains  an  equivalent  of  about  90  per  cent, 
creosote  and  is  employed  as  an  inhalant  in  pulmonary 
tuberculosis  and  as  an  intestinal  antiseptic.  Sp.  gr.,  I'l^S 
to  1-1696. 

CRESINEOL — A  crystalline  antiseptic  compound  of  cineol 
and  cresol,  with  a  melting-point  of  55*2°  C. ;  soluble  in 
most  organic  solvents,  and  decomposable  by  alkaline 
hydrates ;  indicated  for  use  as  an  intestinal  antiseptic  and 
as  a  dusting  powder. 

CRESOL  (C7H8O  or  CH3,C6Hf  OH),  obtained  from  coal  tar  and 
present  in  the  tar  from  pine  and  beech  wood,  is  a  homo- 
logue  of  phenol  (C6H6O  or  C6H5OH).  There  are  three 
isomeric  forms,  named  respectively  ortho-,  meta-,  and  para- 


CRESOL— CR  UCIBLES  143 

CRESOL  (Continued)— 

cresol.  Orthocresol  is  a  crystalline  solid  body  which  melts 
at  30°  C.  Metacresol  is  a  liquid  boiling  at  200°  C. 
Paracresol  is  a  white  crystalline  body  which  melts  at  36°  C. 

Crude  liquid  cresol  as  obtained  by  the  distillation  of  tar 
can  be  rendered  soluble  in  or  miscible  with  water  by  the  use 
of  resin  or  oil-soap  and  alkali,  and  in  this  form  it  constitutes 
the  basis  of  many  disinfectant  preparations.  Of  the  cresols 
(all  of  which  exhibit  strong  germicidal  properties),  meta 
cnsol  outstrips  its  two  isomerides  in  this  qualification. 

Useful  application  has  been  made  industrially  in  respect 
of  the  capability  of  cresol  for  absorbing  many  vapours  by 
solvent  action,  as,  for  example,  those  of  ether-alcohol. 

CRESYLIC  ACID — Another  name  for  cresol. 

CRITH— The  weight  of  a  litre  of  hydrogen  at  standard 
temperature  and  pressure — viz.,  0*0896  gramme. 

CROCOISITE— See  Chromium. 

CROOKESITE — A  rare  mineral  containing  thallium,  asso- 
ciated with  copper  and  silver  in  the  form  of  selenides 
(Cu2Se,TlSe,Ag2Se).  (See  Thallium.) 

CROTON  OIL  is  a  fatty,  yellowish-brown  liquid,  with  a  sp.  gr. 
of  0-940  to  0-960,  of  rancid  odour,  expressed  from  the 
seeds  of  Croton  tiglium  between  hot  plates.  It  is  contained 
to  the  extent  of  about  50  per  cent.,  is  soluble  in  alcohol 
and  ether,  and  contains  an  oily  active  principle  named 
crotonol  (C9H14O2)  to  the  presence  of  which  it  owes  its 
drastic  purgative  property  and  its  irritating  action  on  the 
skin. 

CRUCIBLES— Vessels  or  pots  employed  for  heating  solid 
chemical  substances  to  a  high  temperature  or  for  melt- 
ing metals,  etc.  They  are  variously  made  of  earthen- 
ware, plumbago,  porcelain,  silica,  platinum,  iron,  silver,  and 
nickel,  but  the  metallic  ones  may  not  be  employed  for 
melting  metals  or  under  circumstances  in  which  another 
metal  may  be  reduced  from  the  compound  in  use  to  its  free 
(uncombined)  state,  on  account  of  the  danger  of  damaging 
or  ruining  the  vessel  through  the  production  of  an  alloy 
(see  Alloys) — that  is,  a  combination  of  the  other  metal  with 
the  metal  of  the  crucible. 

Amongst  other  practical  applications  of  crucibles  may  be 
mentioned  their  employment  for  incinerating  compounds 
of  partly  organic  nature  with  the  view  of  burning  off  the 
organic  constituents.  Platinum  crucibles  are  commonly 


144  CRUCIBLES- CRYSTALS 

CRUCIBLES  (Continued)— 

used   in   chemical  laboratories  for  fusing   inorganic   sub- 
stances. 

Gooch  Crucible — A  cup  of  glazed  porcelain,  usually  about 
1 1  inches  high  and  of  ij  inches  diameter  at  the  top, 
tapering  somewhat  to  the  bottom,  which  is  pierced  with 
a  number  of  small  holes.  A  layer  of  asbestos  is  laid 
on  this  by  pouring  a  suspension  in  water  of  the  finely 
divided  material  into  the  cup,  and  allowing  it  to  drain  ; 
then  a  perforated  porcelain  plate  is  laid  on  top  of  the 
asbestos  "  mat." 

The  crucible  is  fitted  into  the  neck  of  a  vacuum  flask,  in 
which  low  pressure  is  maintained  by  a  filter-pump. 

This  arrangement  serves  for  the  filtration  of  solutions 
which  would  pass  only  very  slowly  through  an  ordinary 
paper  filter  or  would  act  on  it  chemically. 

The  crucible  with  the  precipitate  can  be  dried  and  ignited 
for  weighing. 

CRYOHYDRATES— See  Solution. 
CRYOLITE — See  Aluminium  and  Fluorine. 

CRYSTALS — Substances  of  definite  symmetrical  or  geometrical 
form — the  reverse  of  the  amorphous  state — classified  as 
follows : 

(1)  The  regular    or   cubical    system,    as,    for   example, 
salt,  alum,  and  the  diamond. 

(2)  The  quadratic  or  tetragonal  system,  of  which  potas- 
sium dihydrogen  phosphate,  potassium  ferrocyanide,  and 
tinstone  are  examples. 

(3)  The  rhombic  or  orthorhombic  system,  as  exemplified 
by  potassium  sulphate  and  nitre. 

(4)  The  monoclinic  or  monosymmetric  system,  as  gypsum, 
borax,  and  soda  crystals. 

(5)  The  triclinic  or  anorthic  system,  as  copper  sulphate 
and  potassium  dichromate. 

(6)  The  hexagonal  system — quartz  and  lead  iodide,  for 
examples. 

Many  chemical  bodies  assume  the  crystalline  state  when 
they  change  from  the  liquid  or  gaseous  condition  into 
the  solid  form.  They  are  produced,  for  instance,  by  the 
evaporation  of  saturated  solutions,  and  upon  cooling  of 
fused  masses  such  as  of  sulphur  and  antimony,  or  by  sub- 
limation as  with  iodine,  phosphorus,  and  arsenious  oxide. 

The  diamond  and  many  other  precious  stones  probably 
result  from  processes  of  fusion  effected  under  great  pressure, 


CRYSTALS  145 

CRYSTALS  (Continued)— 

and  a  very  large  number  of  definite  chemical  bodies  are 
found  in  nature  in  a  crystalline  condition. 

Isomorphous  analogous  chemical  substances  can  replace 
each  other  wholly  or  partially  in  many  crystalline  com- 
pounds without  alteration  of  the  crystalline  form. 

It  has  been  stated  as  a  statistical  truth  that  everything 
strives  towards  symmetry  in  so  far  as  the  environment  will 
allow  ;  and  it  has  lately  been  proved  that  charcoal  is  really 
crystalline,  and  that  the  so-called  colloidal  particles  of  silver 
and  gold  are  in  reality  ultra-microscopical  crystals. 

Crystalline  bodies  exhibit  a  peculiar  susceptibility  to 
cleavage — that  is,  being  split  in  some  directions  more  readily 
than  in  others,  and  of  allowing  heat  and  light  rays  to  pass 
more  readily  in  certain  directions  as  compared  with  others, 
thus  giving  rise  to  the  phenomena  of  double  refractjon. 

The  arrangement  of  the  atoms  in  many  of  the  simpler 
crystalline  forms  is  stated  to  have  been  determined  by 
X-ray  analysis.  In  certain  cases,  such  as  that  of  potassium 
chloride,  every  atom  occupies  a  symmetrical  position  in  the 
crystal  structure,  each  potassium  atom  being  symmetrically 
surrounded  by  six  chlorine  atoms,  and  each  chlorine  atom 
by  six  potassium  atoms. 

In  the  diamond,  every  carbon  atom  is  symmetrically  sur- 
rounded by  four  other  carbon  atoms,  arranged  at  the  corners 
of  a  tetrahedron  in  such  manner  that  the  whole  crystal  is 
one  continuous  molecule,  thus  explaining,  as  is  thought,  its 
great  density  and  hardness. 

It  would  also  appear  that  the  internal  molecular  structure 
of  crystals  is  such  that  the  maximum  electrostatic  stability 
is  attained.  The  subject  is  too  complicated  to  be  further 
explained  in  a  work  of  this  character,  but  its  continued  study 
is  likely  to  throw  considerable  light  upon  atomic  structures 
and  their  connection  with  electrons.  (See  Atoms,  Electrons, 
and  Radio-activity. 

Little  or  nothing  is  known  of  the  determining  causes  of 
the  formation  of  crystals,  and  this  is  illustrative  of  the  fact 
that  scientists  stand  only  on  the  threshold  of  knowledge 
regarding  primordial  matter  and  primary  causes. 

Substances  capable  of  assuming  crystalline  form  are 
classified  as  crystalloids  to  distinguish  them  from  colloids — 
that  is,  substances  which  cannot  be  crystallized — and  from 
the  larger  class  of  amorphous  substance. 

Isomorphous  substances  are  those  which  crystallize  in 
the  same  form,  such  as  the  sulphates  of  zinc  and  mag- 
nesium, whereas  when  a  substance  (such  as  sulphur)  is 

10 


146  CRYSTALS— CUBEBS 

CRYSTALS  (Continued)— 

capable    of    crystallizing    in    two     forms     it     is     termed 
dimorphous. 

The  view  is  generally  held  that  when  two  substances 
have  forms  identical  in  crystallographic  system  they 
contain  an  identical  number  of  atoms  similarly  united. 
(See  Amorphous  and  Colloids  ;  also  Dialysis.) 

CRYSTALLIZATION  —  The  act  of  crystallizing.  If,  for 
example,  some  common  alum  be  dissolved  in  cold  water 
until  it  will  dissolve  no  more,  or  in  other  words,  until  the 
solution  is  saturated  at  that  temperature,  and  then  trans- 
ferred to  an  evaporating-dish  and  more  alum  dissolved  by  the 
aid  of  heat  until  again  the  solution  is  saturated  at  this  higher 
temperature,  it  will  upon  cooling,  deposit  a  mass  of  crystal- 
lized alum — viz.,  that  further  quantity  which  was  dissolved 
by  the  aid  of  applied  heat. 

As  a  rule,  crystals  are  of  larger  size  when  solutions  of  salts 
are  not  too  concentrated  and  are  allowed  to  cool  slowly. 

Some  liquids  exhibit  a  suspension  of  crystallization  or 
solidification — for  example,  glycerine  may  be  cooled  to 
-  30°  C.  without  solidifying,  but  upon  the  addition  of  a 
crystal  of  the  solid  substance,  the  whole  quantity  freezes  at 
once  and  will  not  melt  again  until  a  temperature  of  15*5°  C. 
is  reached. 

Crystallization  is  often  resorted  to  as  a  means  of  purify- 
ing a  particular  constituent  of  a  solution  from  accompany- 
ing and  less  crystalline  substances  or  bodies  devoid  of 
crystalline  form. 

Many  chemical  salts  have  the  property  of  combining 
with  water  in  assuming  the  crystalline  form  from  a  state  of 
solution :  thus  cupric  sulphate,,  which  has  the  formula  CuSO4, 
in  its  anhydrous  form,  crystallizes  from  water  in  chemical 
combination  with  5  molecules  of  water  (CuSO4,5H2O), 
magnesium  sulphate  with  7  molecules  (MgSO4,7H2O),  and 
so  on,  and  water  so  combined  is  termed  "  water  of  crystal- 
lization." This  water  of  crystallization  is,  generally,  expelled 
from  salts  by  heating  to  100°  C.,  or  by  exposure  in  vacua . 

CRYSTALLOIDS— See  Crystals. 

CUBEBS,  OIL  OF— The  volatile  oil  of  cubebs,  the  fruit  of 
Piper  cubeba  L.,  a  native  of  Java,  obtained  by  distillation 
with  water.  It  is  of  pale  green  colour  or  colourless,  thick, 
of  aromatic  odour,  is  soluble  in  alcohol  and  ether,  and  finds 
some  application  in  medicine.  Its  sp.  gr.  is  0*905  to  0*92, 
refractive  index  1*495  to  I'49^>  and  rotation  -25°  to  -40°. 


CUDBEAR— CUTTLE-FISH  147 

CUDBEAR — A  colouring  matter  prepared  from  certain  lichens 
— like  Archil. 

CULM— Anthracite. 

CUMENE  (C9H12) — A  liquid  homologue  of  benzene,  of  sp. 
gr.  0-862,  existing  ready  formed  in  Burmese  naphtha,  and 
produced  by  the  distillation  of  cumic  acid  (C10H12O2),  or 
by  heating  a  mixture  of  cumic  acid  and  baryta.  It  is 
soluble  in  alcohol  and  ether,  and  used  for  sterilizing  catgut. 

CUPELLATION — An  operation  conducted  in  a  cupel — that  is, 
a  shallow,  oval-shaped,  bone-earth  or  other  dish  which  is 
heated  in  a  reverberatory  furnace  in  course  of  assaying  or 
testing  of  metals  or  ores ;  for  example,  argentiferous  lead, 
rich  in  silver,  which,  when  treated  in  this  way  in  a  current 
of  air,  is  decomposed,  the  lead  being  converted  into  oxide 
(litharge),  which  melts  and  is  absorbed  by  the  bone-earth 
cupel,  or  is  blown  over  by  the  air-current,  leaving  the 
metallic  silver  in  the  cupel. 

CUPFERRON  (C6H5(NO)ONH4)— The  ammonium  salt  of 
nitrosophenylhydroxylamine.  It  is  a  crystalline  body  soluble 
in  water,  used  in  the  practice  of  quantitative  analysis  for 
separating  copper  and  iron  from  other  associated  metals, 
they  alone  being  precipitated  by  cupferron  from  strongly 
acid  solutions.  The  precipitate  is  washed  on  a  filter  first 
with  water  and  then  with  ammonium  hydrate,  which  dis- 
solves the  copper  but  not  the  ferric  compound,  which  is 
soluble  in  chloroform,  ether,  and  acetone,  and  may  thus  be 
obtained  free  from  other  associated  metallic  salts. 

The  ferric  compound  can  be  converted  into  oxide  by 
ignition  and  weighed  as  such. 

Its  use  is  limited  by  reason  of  its  explosive  character. 

CUPRITE— A  mineral  copper  oxide  (Cu2O). 

CURARA — A  resinous  body  extracted  from  plants  of  the 
genus  strychnos,  and  used  by  the  Indians  of  South  America 
for  poisoning  their  arrows.  The  active  principle  is  named 
curarina,  a  yellow  substance,  soluble  in  water  and  alcohol. 

CURCUMIN— Turmeric  yellow. 

CUTCH — A  tanning  material,  being  the  catechu  of  the  Mimosa 
catechu  or  Acacia  catechu.  It  is  a  hard  brownish-black 
substance  prepared  in  India,  and  is  apparently  of  glucoside 
character.  (See  Catechu  and  Tannins.) 

CUTTLE-FISH — A  molluscous  animal  of  the  order  Cephalopoda 
and  genus  sepia,  possessing  a  so-called  "ink-bag" — a  gland 
near  the  liver — from  which  it  discharges,  when  pursued, 
a  dark-coloured  liquid,  which  discolours  the  water  and 


148  CUTTLE-FISH— CYA  N1DES 

CUTTLE-FISH  (Continued)— 

obscures  its  passage.  It  is  from  this  material  that  the 
sepia  of  painters  is  prepared,  by  dissolving  it  in  potassium 
or  sodium  hydrate,  reprecipitation  with  hydrochloric  or 
sulphuric  acid,  washing  and  drying.  Sepia  is  dark  brown 
in  colour  and  of  fine  grain,  and  is  stated  to  consist  of  a 
mixture  of  calcium  and  magnesium  carbonates,  melanin, 
and  an  organic  colouring  matter. 

CYANAMIDE  (CN2H2)  is  a  colourless,  crystalline  body,  pre- 
pared from  cyanogen  chloride  and  an  ethereal  solution  of 
ammonia.  It  is  deliquescent,  melts  at  40°  C.,  is  soluble  in 
water,  alcohol,  and  ether,  and  behaves  chemically  both  as 
a  weak  base,  forming  crystalline  salts  with  acids,  and  as  a 
weak  acid,  yielding  sodium,  lead,  silver,  and  calcium  com- 
pounds. The  calcium  derivative  is  commercially  produced 
by  heating  calcium  carbide  to  about  1,000°  C.  (in  the 
presence  of  a  little  calcium  chloride)  in  a  current  of  air  or 
nitrogen — 

CaC2  +  N2=CaCN2  +  C, 

or  by  passing  nitrogen  over  a  mixture  of  lime  and  carbon 
electrically  heated  to  2,000°  C.,  an  excess  of  carbon  being 
used.  The  crude  product  is  a  black  powder  containing 
from  20  to  23  per  cent,  of  nitrogen,  and  is  used  as  a 
fertilizing  agent  under  the  name  of  "  nitro-lime."  The 
other  constituents  of  nitro-lime  are  about  20  per  cent,  of 
free  lime,  7  to  8  per  cent,  of  silica,  alumina,  and  iron,  and 
14  per  cent,  of  carbon  in  the  form  of  graphite. 

Under  the  influence  of  superheated  steam,  cyanamide 
gives  off  its  nitrogen  in  the  form  of  ammonia.  (See  Calcium 
Carbide.) 

CYANIC  ACID  (CNHO)  is  a  mobile  liquid  of  pungent  odour 
and  unstable  nature,  changing  with  explosive  violence  into 
cyanuric  acid  and  cyamelide  when  removed  from  a  freezing 
mixture.  By  combination  with  bases  it  forms  cyanates, 
including  ammonium  cyanate,  which  gradually  undergoes 
change  at  ordinary  temperatures,  and  at  100°  C.  is  quickly 
resolved  into  urea,  as  expressed  by  the  following  formula — 

CNO(NH4)  =  CO(NH2)2. 

This  is  a  striking  instance  of  isomeric  change  by  atomic 
reconstruction  brought  about  by  a  physical  cause.  (See 
Isomerism.) 

Potassium   cyanate   is  a  white   crystalline   salt   readily 
soluble  in  water  and  alcohol. 
CYANIDES — See  Hydrocyanic  Acid  and  Cyanogen. 


CYANOGEN— DARIN'S  SOLUTION  149 

CYANOGEN  (C2N2) — A  very  poisonous,  colourless  gas,  soluble 
in  water  and  alcohol,  having  an  odour  something  like  that 
of  bitter  almonds,  and  which  behaves  in  many  respects  as 
a  halogen,  the  group  CN  playing  the  part  of  a  radical, 

It  is  obtained  by  heating  mercuric  cyanide  and  collecting 
it  over  mercury  (as  it  is  soluble  in  water),  and  can  be  con- 
densed to  a  colourless  liquid  of  sp.  gr.  i'8.  It  is  inflam- 
mable, and  when  burned  it  is  resolved  into  carbon  dioxide 
and  nitrogen. 

In  combination  with  hydrogen  it  forms  hydrocyanic 
acid  (HCN).  (See  Hydrocyanic  Acid.)  Carbon  and 
nitrogen  do  not  combine  directly,  but  heated  together  with 
an  alkali  such  as  potassium  carbonate,  the  corresponding 
cyanide  is  formed — in  this  case,  potassium  cyanide  (KCN). 
The  cyanides  of  the  alkali  and  alkali-earth  metals  are  all 
soluble  in  water,  but  those  of  the  heavy  metals,  excepting 
mercury  cyanide,  are  insoluble  in  water.  The  potassium 
and  sodium  cyanides  are  largely  used  in  the  extraction  of 
gold  and  silver  from  their  ores,  also  in  electro-plating  and 
other  industries. 

Cyanogen  compounds  are  made  on  an  extensive  scale 
from  nitrogenous  organic  matters,  such  as  the  clippings 
of  hoofs  and  hides  ;  thus,  when  heated  with  iron  and  potash, 
potassium  ferrocyanide  is  produced.  (See  Potassium.) 

"  CYLLIN  " — A  proprietary  coal-tar  disinfectant  fluid,  emul- 
sifying with  water. 

CYMENE  (C10H14),  also  known  as  cymol,  is  found  present  in 
the  volatile  " cummin"  oil  (obtained  from  Cuminum cyminum) 
in  water-hemlock  seeds,  and  in  oil  of  thyme.  It  is  nearly 
related  to  camphor  (C10H16O)  (from  which  it  can  be  readily 
obtained  by  a  process  of  dehydration)  and  to  the  terpenes 
(C10H16),  from  which  it  can  also  be  prepared.  It  boils  at 
175°  C.,  has  a  sp.  gr.  of  0-856,  is  soluble  in  alcohol  and 
ether,  is  colourless,  and  has  an  agreeable,  somewhat  cam- 
phoraceous  and  lemon-like  odour. 

CYTASE — One  of  the  enzymes  in  germinating  barley  which 
attacks  and  destroys  the  cell  walls,  thus  exposing  the  starch 
content  to  the  action  of  the  diastase. 

DAKIN'S  SOLUTION — An  antiseptic  liquid,  10  litres  of  which 
can  be  prepared  according  to  the  following  approved 
formula:  chloride  of  lime,  say  156  grms. ;  anhydrous 
sodium  carbonate,  78  grms. ;  anhydrous  sodium  bicarbonate, 
65  grms.  The  chlorinated  lime  is  first  of  all  digested  with 
5  litres  of  water  and  subsequently  filtered,  and  the  other 


i5o  DA  KIN'S  SOLUTION— DECOMPOSITION 

DAKIN'S  SOLUTION  (Continued)— 

ingredients  are  then  dissolved  in  water,  and  the  solution 
mixed  with  that  of  the  chloride  of  lime  and  made  up  to 
10  litres.  (See  Eau  de  Javelle.) 

DAMMAR  A  RESIN  (Dammar  gum)  of  commerce  melts  at 
about  120°  C,,  and  is  of  two  varieties,  one  of  which  is 
known  also  as  "cowdie  gum,"  the  produce  of  a  large 
conifer  (Dammara  australis),  which  occurs  in  whitish-yellow 
masses  and  smells  like  turpentine. 

The  other,  of  East  Indian  origin  and  known  also  as  "  cat's- 
eye  resin,"  comes  in  the  main  from  Singapore  and  is  the  pro- 
duce of  another  coniferous  tree  (Pimis  dammara  or  Dammara 
alba).  It  has  a  resinous  odour  and  is  the  better  known  of  the 
two  varieties. 

Both  kinds  are  soluble  in  turpentine,  alcohol,  and  ether, 
and  are  used  in  the  manufacture  of  varnishes  and  lacquers. 

DANAITE — A  cobaltiferous  mispickel. 

DEAD  OIL— The  "  heavy  "  oil  obtained  from  the  distillation  of 
coal  tar. 

DEOANTATION — Pouring  off  or  decanting  a  liquid  from  a 
sediment  or  deposit.  (See  also  Siphon.) 

DECOCTION — An  infusion  or  extract  prepared  by  heating  or 
boiling  a  crude  material  with  a  solvent  for  the  purpose  of 
extracting  its  soluble  constituents. 

DECOMPOSITION — A  chemical  compound  can  be  broken  up 
into  its  constituent  parts  by  chemical  or  physical  means, 
and  is  then  said  to  be  decomposed.  Decomposition  is  the 
breaking  up  of  a  compound  into  its  parts  by  means  of  a 
greater  force  than  that  of  the  chemical  affinity  which  binds 
them  together. 

There  are  many  ways  or  methods  of  effecting  the  decom- 
position of  chemical  compounds.  Some  can  be  readily 
decomposed  by  heating  ;  in  others  an  electric  current 
passed  into  them  in  a  molten  state  or  into  their  solutions 
will  effect  the  purpose ;  whilst  in  yet  other  cases  mere 
exposure  to  light  suffices,  many  of  the  silver  compounds, 
for  example,  suffering  chemical  change  in  this  way,  and 
practical  advantage  of  this  fact  is  taken  in  the  art  of 
photography. 

Water  consists  of  a  combination  of  two  gases,  named 
hydrogen  and  oxygen,  and  it  can  be  decomposed  or  broken  up 
into  them  again  by  passing  a  current  of  electricity  through  it. 


DECOMPOSITION— DEGRA  S  151 

DECOMPOSITION  (Continued)— 

Limestone,  of  which  the  common  limestone  rock  is 
chiefly  composed,  is  a  chemical  combination  of  lime  and 
carbon  dioxide,  and  when  it  is  strongly  heated — as  is  done 
practically  in  lime-kilns — it  is  broken  up  or  decomposed 
into  the  two  parts.  The  lime  which  is  left  in  the  kiln  is 
itself  a  chemical  compound  of  a  more  simple  nature,  con- 
sisting as  it  does  of  the  metal  calcium  and  the  gas  oxygen, 
whilst  the  carbon  dioxide  gas  which  escapes  from  the  kiln 
is  also  a  chemical  compound  of  an  element  named  carbon 
(which  forms  the  chief  constituent  of  charcoal  and  the 
precious  stones  known  as  diamonds)  with  oxygen  (which  is 
one  of  the  constituent  gases  of  air). 

The  yellow  mercury  oxide  can  be  broken  up  or  decom- 
posed into  its  two  constituents  by  exposing  it  to  a  greater 
heat  than  that  which  is  necessary  to  produce  it  from  the 
mercury  and  oxygen  of  which  it  is  composed. 

DECORTICATION— The  shelling  of  seeds  intended  to  be  sub- 
sequently crushed  to  extract  the  oil  contained  in  them  by 
pressure  or  the  action  of  solvents. 

DECREPITATION — Physical  rending  or  flying  apart  of  the 
joints  of  the  crystalline  structure  of  certain  minerals  and 
salts  when  heated,  attended  with  a  crackling  noise.  Com- 
mon salt  and  calcspar  exhibit  this  behaviour. 

DEFECATION — Processes  of  purification  or  freeing  from 
dregs. 

DEFLAGRATION—A  rapid  combustion  with  evolution  of  light 
and  heat,  as  when  a  strip  of  magnesium  foil  is  burned  in 
oxygen  gas.  A  mixture  of  nitre  with  antimonious  sulphide, 
thrown  into  a  red-hot  crucible,  burns  with  deflagration,  the 
sulphur  being  oxidized  by  the  oxygen  of  the  nitre. 

DEFLAGRATING-SPOON— A  metallic  wire  or  rod  terminating 
at  the  lower  end  in  a  small  iron  or  other  metallic  spoon  or 
cup  to  hold  the  desired  chemical  substance,  and  fitted  above 
with  a  metallic  plate  or  with  a  cork,  which  may  be  adjusted 
beforehand,  to  fit  a  wide-mouthed  stoppered  jar  or  bottle, 
in  which  it  is  planned  to  make  the  experiment. 

Such  an  appliance  can  be  used  to  illustrate  the  burning 
of  phosphorus  in  oxygen  gas  as  referred  to  under  the 
heading  of  Chemical  Interactions. 

DEGRAS — A  crude  grease  obtained  from  sheep's  wool,  used  as 
a  leather  dressing.  (See  also  Adeps  Lanae  and  Suint.) 


152  "  DEKA LINE  "—DEPILATORIES 

11 DEKALINE  "  (Decahydronaphthaline)  (C10H18)— A  proprie- 
tary substitute  for  turpentine,  used  as  a  solvent,  also  as  a 
substitute  for  lamp,  motor,  and  lubricating  oils,  with  a  dis- 
tilling-potnt  of  190°  C.,  flash-point  60°  C.,  and  sp.  gr.  0-9. 
It  is  prepared  by  treating  naphthaline  in  a  fused  state  and 
at  a  temperature  above  100°  C.  with  hydrogen  in  the 
presence  of  a  catalyst  such  as  finely  divided  nickel.  It  is 
of  aromatic  character,  with  an  odour  something  like  that  of 
camphor,  and  can  be  used  as  a  cleansing  fluid  for  machinery, 
particularly  printing  machines,  and  for  removing  stains 
from  garments.  As  a  solvent,  it  is  stated  to  be  equal  to 
turpentine,  and  it  is  somewhat  slower  in  evaporation  than 
that  liquid,  which  is  a  point  in  its  favour  for  some  applica- 
tions. 

DELIQUESCENCE— Absorption  of  moisture  from  the  air, 
whereby  substances  become  pasty  or  more  or  less  liquid  in 
character;  common  salt,  for  example,  is  a  deliquescent 
substance,  and  calcium  chloride  is  a  very  deliquescent 
compound.  (See  Drying-Tube.) 

Some  crystalline  substances  when  exposed  to  the  air 
combine  with  the  moisture  contained  therein  and  pass  into 
other  distinct  crystalline  forms,  and  in  certain  instances  the 
combination  continues  to  such  an  extent  that  the  substance 
liquefies. 

DELPHININE  (C22H35NO6) — A  white,  crystalline,  poisonous 
alkaloid,  soluble  in  alcohol  and  ether,  extracted  from  the 
seeds  of  Delphinium  staphisagria,  or  larkspur. 

DEN  ATURANTS— Substances  introduced  into  alcohol  made 
for  industrial  purposes  to  prevent  its  consumption  as  drink, 
such  as  paraffin  oil,  pyridine,  camphor,  and  benzene. 

DENSITIES — Relative  weights  compared  with  a  standard. 
Water  is  taken  as  a  standard  of  comparison  for  liquids  and 
solids,  whilst  hydrogen  gas  is  ordinarily  taken  as  that  of 
gases.  (See  Hydrometer,  Molecules,  and  Specific  Gravity.) 

DEOXIDATION — The  taking  away  of  oxygen  as  a  constituent 
of  a  substance;  for  instance,  iron  oxide  is  deoxidized  by 
heating  with  carbonaceous  material,  as  in  smelting,  thus 
reducing  it  to  the  metallic  state.  Barium  dioxide  is  de- 
oxidized to  the  state  of  barium  monoxide  by  heating  it  to  a 
certain  temperature. 

DEPILATORIES — Chemicals  used  for  the  removal  of  hair  from 
skins,  such  as  the  alkaline  sulphides  used  in  the  leather 
industry. 


DERBYSHIRE  SPAR— DEVITRIFICATION  153 

DERBYSHIRE  SPAR— See  Fluorine. 
DERMATOL— Bismuth  subgallate,  used  in  medicine. 
DESICCATE— To  dry,  denude,  or  rob  of  water. 

DESICCATOR — A  drying  appliance  designed  to  remove  water 
from  chemical  substances.  A  common  form  consists  of  a 
segmented  porcelain 
basin  containing 
strong  sulphuric 
acid,  standing  on  a 
glass  plate  having  a 
ground  surface  and 
covered  with  a  closed 
bell-jar,  having  also 
ground  edges  slightly 
coated  with  grease. 
The  liquid  or  solid 
preparation  to  be 

dried  (desiccated) -is  pi 

placed  in  a  smaller 

vessel     Of    glass     Or  .N  B  _Th;s  pigure  of  an  Air-Putnp  and  Desic- 
platmum     Or      Other      cator  does  not  show  the  Sulphuric  Acid  Basin. 

material  on  the  ves- 
sel containing  the  strong  sulphuric  acid,  which,  having  a 
strong  affinity  for  water,  absorbs  the  moisture  evaporated 
from  the  substance  undergoing  the  drying  process.  Some- 
times this  appliance  is  coupled  up  with  an  air-pump  to 
facilitate  the  process.  By  greasing  the  plate  as  well  as 
the  edges  of  the  bell-jar,  the  combination  is  made  airtight. 
(See  Air- Pump.) 

DETONATORS — Copper  tubes  containing  a  charge  of  mercuric 
fulminate  alone  or  mixed  with  potassium  chlorate  or  other 
ingredients.  Other  detonating  substances  include  an 
aniline  derivative  named  "  tetryl "  (tetranitroaniline),  lead 
triazide  (PbN6),  etc.  Detonation  requires  to  be  started  by 
a  strong  impulse  such  as  that  imparted  by  the  explosion  of 
a  charge  of  mercury  fulminate ;  it  proceeds  very  rapidly, 
and  is  due  to  the  formation  of  an  explosion  wave  having  a 
velocity  of  thousands  of  metres  per  second. 

In  blasting  operations  detonators  (like  gunpowder)  are 
either  fired  by  a  time-fuse  or  electrically. 

DETRITUS— Redeposited  matter  worn  off  rocks. 

DEVITRIFICATION— Loss  of  opacity  or  vitreous  character  of 
glass. 


1 54  DE  W-POINT—DIA  STA  SE 

DEW-POINT — The  temperature  at  which  the  atmospheric  air 
is  saturated  with  moisture  and  begins,  in  consequence,  to 
deposit  it.  (See  Air,  p.  9.) 

DEXTRINE— See  Starch. 

DEXTRO-LIMONENE— A  terpene  (C10H16)  constituent  of 
several  essential  oils. 

DEXTROSE  (C6H12O6)  — A  soluble  carbohydrate,  dextro- 
rotatory in  character,  and  otherwise  known  as  glucose  and 
grape-sugar,  prepared  from  cane-sugar  by  inversion  and 
from  starchy  bodies  by  action  of  mineral  acids ;  but,  as 
thus  made,  it  contains  dextrine  and  other  unfermentable 
bodies  in  association.  It  is  largely  used  in  brewing,  con- 
fectionery, preparing  tobacco,  and  in  chrome  tanning 
liquors.  (See  Invertase.) 

DIABANTITE — An  uncommon  member  of  the  chlorite  group 
of  complex  mineral  silicates. 

DIALYSIS — A  sort  of  diffusion  by  means  of  which  a  liquid 
which  contains,  say,  a  mixture  of  a  crystallizable  substance 
such  as  salt  or  sugar,  with  another  (colloid)  which  is  not 
crystallizable,  such  as  albumin  or  gum,  can  be  separated. 
This  is  effected  by  placing  the  mixture  jn  a  tray  or  other 
vessel  having  as  its  bottom  a  sheet  of  parchment  paper  or 
animal  membrane,  such  as  bladder,  etc.,  and  floating  or 
suspending  this  vessel  in  a  dish  of  water,  when  the  crystal- 
lizable substance  in  solution  dialyzes  or  diffuses  through  the 
parchment  dialyzer  into  the  water  outside,  and  the  colloidal 
substance  in  solution  remains  behind  in  the  containing 
vessel.  Colloidal  solutions  are  not  utterly  devoid  of  the 
property  of  diffusion,  but  as  the  size  of  the  constituent 
particles  is  great  in  comparison  with  that  of  the  molecules 
they  diffuse  very  slowly  as  compared  with  crystalloids. 
(See  Colloid  and  Osmosis.) 

DIAMINOPHENOL  (C6H4(NH2)C6H5)— The  ortho  and  para 
varieties  of  this  substance  are  greyish-white  and  crystalline, 
and  are  used  as  photographic  developers. 

DIAMOND — The  purest  form  of  crystallized  carbon,  the  sp. 
gr.  of  which  is  3-5.  It  is  of  great  hardness.  There  are 
deposits  in  South  Africa,  Brazil,  India,  and  elsewhere. 

DIAPHANOUS— Transparent  to  light. 

DIASTASE — An  amorphous  active  principle  or  enzyme, 
soluble  in  water,  contained  in  extract  of  malt,  capable  of 
turning  starch  into  soluble  substances,  including  ferment- 
able sugar.  (See  Beer,  Enzymes,  and  Malt.) 


DIA  THERM  A  NO  US— DIFFUSION  1 5  5 

DIATHERM ANGUS— A  character  of  substances  like  rock- 
crystal  which  transmit  heat  as  transparent  substances 
transmit  light. 

DIATOMITE  (Diatomaceous  Earth)— A  form  of  kieselgiihr  or 
siliceous  deposit.  (See  Silicon.) 

DICHROISM — The  property  possessed  by  double-refracting 
crystals  of  exhibiting  two  colours  when  viewed  in  different 
directions.  (See  Crystals  and  Fluorescence.) 

DIET— See  Foods. 
DIETHYLAMINE— See  Amines. 

DIETHYLANILINE  (C6H5.N(C2H5)2)— A  yellowish-brown,  in- 
flammable liquid  obtained  by  heating  a  mixture  of  aniline, 
aniline  hydrochloride,  and  ethyl  alcohol.  It  boils  at 
2i3'5°  C.,  is  soluble  in  alcohol  and  ether,  and  employed  in 
the  manufacture  of  synthetic  dyes. 

DIFFUSION — Widely  spreading  or  extending;  a  property 
particularly  exhibited  by  gases,  all  of  which  mix  together 
or  diffuse  into  each  other  without  chemically  combining 
and  in  a  much  more  complete  sense  than  certain  liquids 
are  miscible  with  each  other.  The  relative  velocities  of 
diffusion  of  any  two  gases  are  inversely  as  the  square  roots 
of  their  densities. 

Vinegar  and  water  placed  together  in  a  bottle  and  shaken, 
gives  a  mixture  of  dilute  vinegar  of  which  every  drop 
is  identical  with  every  other  drop.  Other  liquids,  however, 
will  not  mix  together — for  example,  oil  and  water ;  but 
all  gases  will  mix  together.  Oxygen  and  nitrogen,  for 
example,  as  they  exist  in  the  air  are  thoroughly  admixed, 
and  every  part  of  the  air  is  identical  in  composition 
with  every  other  part ;  that  is  to  say,  the  proportions  of 
their  chief  constituents,  oxygen  and  nitrogen,  are  uniform. 
Gases  have  the  property  of  mixing  with,  or  diffusing  into 
each  other  more  than  liquids,  while  solids  have  to  be 
forcibly  mixed  together  to  effect  a  mixture,  and  even  then 
such  a  mixture  is  never  an  absolutely  perfect  one  ;  it  is  only 
at  best  what  may  be  called  an  imperfect  "mechanical" 
mixture.  Some  solids,  such  as  the  metals  tin  and  lead, 
melt  or  fuse  upon  being  heated  sufficiently,  and  in  this 
molten  or  fused  state  some  of  them  can  be  mixed  together. 
(See  Alloys.)  Similarly,  fats  melt  on  the  application  of 
heat,  and  when  melted  they  can  be  mixed  together  (ad- 
mixed). (See  also  Dialysis  and  Osmosis.) 


1 56  DIGEST— DIPENTENE 

DIGEST — To  steep  in  or  expose  a  substance  to  the  digestive 
action  of  a  solvent  liquid. 

DIGESTION  (Animal)— See  Saliva,  Chyme,  Chyle,  Bile,  and 
Pancreatic  Juice. 

DIGITALIS — A  genus  of  plants  of  which  the  common  fox- 
glove is  the  best-known  species  (Digitalis  purpurea),  con- 
taining as  active  principle  digitoxin  or  digitalin  (Q,4H70O14), 
which  is  soluble  in  water  and  actively  poisonous.  The 
herb  itself  is  used  in  medicine  as  a  diuretic  and  for  retard- 
ing circulation. 

DILL  OIL — Distilled  from  the  fruit  of  Anetkum  graveolens, 
contains  limonene  and  carvol,  has  a  sp.  gr.  of  from  0*90  to 
0-92,  optical  rotation  +  70°  to  80°,  and  is  soluble  in  alcohol 
and  ether.  It  is  of  pale  yellow  colour  and  characteristic 
odour,  and  is  used  in  perfumery  and  for  flavouring. 

DILUENTS — Liquids  used  for  diluting  solutions  by  addition 
thereto. 

DILUTE— Weak  in  strength.     (See  Solution.) 
DIMETHYLAMINE— See  Amines. 

DIMETHYLANILINE  (C6H5.N(CH3)2)— An  oily  derivative  of 
aniline  which  boils  at  192°  C.,  has  a  strong  basic  character, 
and  is  used  in  the  synthetic  manufacture  of  dyes.  By  a 
process  of  mild  Oxidation  it  is  converted  into  methyl  violet, 
and  by  a  process  of  reduction  it  yields  the  dye  "  malachite 
green." 

DIMETHYLSULPHATE  ((CH3)?SO4)  is  a  colourless  liquid  of 
sp.  gr.  1 35  and  boiling-point  188°  C.,  with  a  pleasant 
ethereal  odour,  used  for  methylating  amines  and  phenols  in 
the  dyestuffs  and  synthetic  perfumes  industries,  and  has 
also  been  used  as  a  military  poison  gas.  It  is  very 
poisonous ;  its  fumes  produce  violent  inflammation  of  the 
larynx,  bronchial  tubes,  and  eyes,  whilst  the  liquid  blisters 
the  skin  and  produces  bad  sores. 

DIMORPHOUS — The  property  of  crystallization  in  two  forms, 
as  exhibited,  for  example,  by  sulphur.  (See  Crystalliza- 
tion and  Sulphur.) 

DIPENTENE  (C1QH16)— A  sweet-smelling  terpene  constituent 
of  some  essential  oils,  as,  for  instance,  Oleum  cince,  in  which 
it  is  associated  with  lineol.  It  can  be  produced  from  pinene 
by  the  influence  of  dilute  alcoholic  sulphuric  acid  or  from 
sylvestrene  and  other  terpenes  by  several  methods.  Sp.  gr. 
0-85,  boiling-point  181°  to  182°  C. 


DIPPEL'S  OIL— DOLOMITE  157 

DIPPEL'S  OIL — A  very  uncertain  mixture  of  substances  of 
unpleasant  odour  obtained  by  the  destructive  distillation 
of  bones  from  which  the  fat  has  not  been  previously 
abstracted,  as  used  for  the  preparation  of  bone-black.  It 
contains,  amongst  other  constituents,  ammonia,  benzene, 
and  a  number  of  pyridine  bases,  and  has  a  sp.  gr.  of  about 
O'QOO  to  0-980. 

DISINFECTANTS— Preparations  that  destroy  in  any  way 
the  infectants  or  causes  of  disease,  or  render  them 
innocuous. 

DISINTEGRATORS — Machines  for  grinding,  granulating,  or 
shredding  materials. 

DISSOCIATION — Spontaneous  or  forced  acts  of  decomposition. 
For  example,  when  steam  is  heated  sufficiently,  it  is 
forcibly  decomposed  into  hydrogen  and  oxygen,  or,  in  other 
words,  its  constituent  elements  are  dissociated.  Again, 
ammonium  carbonate  on  exposure  to  the  air  breaks  up,  or 
is  dissociated,  into  ammonium  bicarbonate  and  ammonia. 

DISSOLVE — The  act  by  which  a  substance  goes  into  solution, 
as,  for  example,  when  salt  is  dissolved  in  water,  wax  in 
turpentine,  or  oil  in  alcohol.  The  absorption  of  moisture 
by  the  air  is  also  an  act  of  solution. 

DISTILLATION — The  process  of  converting  a  substance  into 
vapour  and  then  condensing  same.  As  applied  to  liquids, 
it  may  be  termed  "  wet  distillation,"  but  the  method  is  also 
used  in  respect  of  many  volatile  solid  substances,  and  it  is 
then  termed  "  dry  distillation."  For  example,  metallic 
mercury  and  zinc  can  be  distilled.  "  Destructive  distilla- 
tion "  means  the  subjection  of  materials  to  heat  to  such 
an  extent  that  they  are  decomposed,  and  it  is  the  products 
of  this  destructive  distillation  that  pass  over  from  the 
retorts  and  are  condensed  fractionally  or  collectively.  This 
occurs  in  the  cases  of  resin  distillation,  coal  distillation, 
the  distillation  of  wood,  and  the  "  cracking  "  of  petroleum. 
(See  Retort.) 

DISTILLED  WATER  is  commonly  used  in  laboratories  for 
making  chemical  reagents  and  for  solvent  and  washing 
purposes  generally,  because  ordinary  water  contains  small 
quantities  of  mineral  substances,  and  requires,  in  fact,  to  be 
distilled  in  order  to  get  rid  of  such  impurities.  (See  Water- 
Oven.) 

DOLOMITE — A  rock  consisting  of  varying  proportions  of 
calcium  and  magnesium  carbonates.  (See  Magnesium.) 


158  DOPE— DRYING-TUBES 

DOPE  is  a  common  name  given  to  various  solutions  or  varnishes 
made  by  dissolving  cellulose  or  cellulose  compounds  in  cer- 
tain solvents,  including  acetone,  amyl  alcohol,  amyl  acetate, 
dichlorethylene  of  sp.  gr.  1*25,  boiling  at  55°  C.  ;  trichlor- 
ethylene  of  sp.  gr.  1-47,  boiling  at  88°  C.;  perchlorethylene 
of  sp.  gr.  1*62,  boiling  at  121°  C. ;  tetrachlorethane  of  sp.  gr. 
1-6,  boiling  at  147°  C.  ;  pentachlorethane  of  sp.  gr.  1-7, 
boiling  at  159°  C.  A  small  addition  of  boric  acid  is  some- 
times made  to  cellulose  dopes  in  order  that  they  may  retain 
their  viscosity.  It  has  been  stated  that  5  to  8  per  cent,  of 
ammonium  phosphate  or  ammonium  magnesium  phosphate 
added  to  cellulose  nitrate  renders  it  fire-resistant,  and 
qualifies  it  to  compete  with  cellulose  acetate  as  an  aero- 
plane dope.  (See  also  Cellulose  and  Viscose.) 

DRAGON'S  BLOOD — A  red  resin  of  several  varieties  secreted 
by  the  fruits  of  a  number  of  palms  of  the  genus  Calamus 
draco,  indigenous  in  Sumatra  and  the  West  Indies.  It 
contains  benzoic  acid  in  combination,  and  is  chiefly  used  for 
colouring  mahogany  varnishes,  in  preparing  gold  lacquers, 
in  compounding  dentifrices,  and  for  staining  marble  a  red 
colour.  (See  Resins.) 

DRIERS — See  Paints  and  Varnishes. 

DROP-BOTTLE — A  simple  appliance  for  providing  drops  of 
liquids  for  testing  purposes,  consisting  of  a  bottle  fitted 
with  a  long,  tapered,  solid  glass  stopper  so  that  when  the 
stopper  is  withdrawn  a  small  quantity  of  the  liquid  adheres 
to  it  and  may  be  dropped  into  any  solution  or  on  to  any 
solid  substance  to  be  tested. 

Another  arrangement  somewhat  similar  is  a  hollow  tube 
or  small  pipette  that  passes  through  the  cork,  and  is  drawn 
out  to  a  fine  point  at  the  lower  end.  By  use  of  the  com- 
pressible rubber  bag  at  the  upper  end  of  the  tube,  as  much 
of  the  liquid  as  is  desired  may  be  retained  in  the  tube  and 
removed  for  testing  purposes. 

DRYING-OVEN— See  Water-Oven. 

DRYING-TUBES— Appliances  used  for  drying  gases  (freeing 
them  from  water),  some  being  straight-shaped  tubes  packed 
with  small  lumps  of  calcium  chloride  (CaCl2),  which  sub- 
stance has  a  great  affinity  for  moisture. 

Another  variety  consists  of  a  U-shaped  tube  sealed  at 
the  bend  with  strong  sulphuric  acid,  as  it  also  has  the 
property  of  absorbing  moisture  contained  in  gases  bubbled 
through  it,  such,  for  example,  as  those  which  are  generated 
by  burning  organic  substances  in  a  current  of  dry  air  or 


DRYING-TUBES— DYER'S  BROOM  159 

DRYING-TUBES  (Continued)  — 

oxygen.  The  increase  in  the  weight  of  the  tube  gives 
the  weight  of  the  water  thus  absorbed,  from  which  may  be 
calculated  the  proportion  of  hydrogen  contained  in  a  known 
weight  of  the  organic  substance  employed.  (See  Organic 
Analyses.) 

DRY  ROT — A  chemical  decomposition  of  wood  or  changes  of 
composition  induced  by  the  agency  of  fungi  (especially 
Polyporus  hybridus  and  Thelaphora  puteana)  and  other  causes ; 
the  proportion  of  carbon  and  hydrogen  contained  in  the 
wood  being  reduced  by  the  production  of  carbon  dioxide 
and  water.  In  other  words,  it  is  an  act  of  slow  oxidation 
accompanied  by  a  loss  of  density  of  the  wood  until  the 
latter,  as  in  the  case  of  hollow  tree  trunks,  becomes  rotten. 
Furniture  and  the  woodwork  of  houses  are  liable  to 
attack  by  the  larvae  of  certain  beetles,  of  which  some  five 
species  occur  in  this  country,  the  common  furniture  beetle 
being  the  Anobium  punctatum  De  J.,  while  the  death-watch 
beetle  Xestobium  rufovillosum  De  J.  more  usually  affects  the 
timber  of  old  houses,  and  the  powder-pest  beetle  (Lyctus) 
mostly  affects  sapwood.  Heat-treatment  is  the  best  remedy 
when  applicable;  otherwise  fumigation  with  a  poisonous 
vapour  such  as  formaldehyde  or  the  application  of  powerful 
insecticides  such  as  "okol,"  benzene,  and  carbon  tetra- 
chloride. 

DUCTILITY — Admitting  of  being  drawn  into  wire.  (See 
Metals.) 

DUGONG  OIL— See  Fish  Oils. 

DULCITOL  or  DULCIN  or  DULCITE  (C6H14O6)— A  white, 
crystalline,  saccharine  body,  soluble  in  water  and  isomeric 
with  mannite  (mannitol),  obtained  from  the  dried  herb 
Melampyrum  memorosum  at  the  flowering  time. 

DUROGLASS — A  trade  name  for  borosilicate  resistance  glass- 
ware. 

"  DUROPRENE  "— A  proprietary  article  in  the  nature  of  a 
chlorinated  rubber  compound  (heptachloride  of  rubber) 
used  in  compounding  paints  for  the  prevention  of  rust  on 
metals,  etc.  It  is  a  greyish-white  powder,  soluble  in 
benzole,  naphtha,  and  carbon  tetrachloride,  and  is  easily 
moulded  when  warmed. 

DYER'S  BROOM  (Genesta  tinctoria) — Found  in  pastures  and 
thickets  in  Southern  Europe,  Russian  Asia,  Southern 
Sweden,  and  some  parts  of  Great  Britain ;  contains  two 
principles,  one  of  which  is  a  yellow  colouring  matter  of 


160  DYER'S  BROOM— DYES  AND  DYEING 

DYER'S  BROOM  (Continued) — 

crystalline   character    and    another  genistein   (C14H]0O5), 
which  can  be  obtained  in  the  form  of  colourless  crystals. 

DYES  AND  DYEING— There  are  an  immense  number  of  dyes, 
some  being  natural  products,  such  as  madder,  indigo, 
logwood,  and  safflower;  but  for  the  most  part,  they  are 
chemically  produced  substances  from  coal-tar  sources  (see 
Intermediates),  and  the  manner  in  which  the  dyes  become 
attached  to  the  fabrics  also  varies  according  both  to  the 
chemical  constitution  of  the  fabrics  themselves  and  those 
of  the  dyes  employed.  In  some  cases,  definite  compounds 
are  formed  by  the  action  of  the  dyes  on  the  fabrics ; 
in  other  cases,  "  lakes "  are  formed  by  the  action  of  a 
mordant,  the  precipitated  substance  being  thus  directly 
attached  to  the  fabrics,  and  in  yet  other  cases  the  dyes  are 
developed  on  the  fibres.  Basic  dyes,  including  mauve, 
magenta,  methylene  blue,  malachite  green,  and  Bismarck 
brown,  are  fixed  on  cotton  goods  by  the  use  of  acidic 
mordants;  acidic  dyes,  including  picric  acid,  azo-scarlets, 
and  aniline  blue,  are  attached  to  wool  and  silk  goods  by  the 
use  of  an  acid-bath.  Other  acidic  dyes,  such  as  alizarin 
red,  require  the  use  of  a  metallic  mordant.  Dyes  of  a  saline 
nature,  like  the  Congo-red  series  and  primulin,  are  used  for 
cotton  and  linen  without  any  mordant,  and  there  are  pig- 
ment dyes,  such  as  chrome  yellow,  synthetic  indigo,  and 
aniline  black,  in  respect  of  which  the  colour  is  developed  on 
the  fibres. 

The  dyestuffs  are  also  classed  as  "substantive"  and 
"  adjective  ":  the  former  have  the  property  of  dyeing  fibres 
directly,  while  the  latter  will  only  colour  them  permanently 
when  used  in  association  with  mordants. 

The  so-called  "  sulphur "  dyes  are  largely  made  from 
dinitrophenol  (C6H3(NO2)2OH),  "sulphur  black"  being 
made  from  it  by  the  action  of  sodium  sulphide  and  sulphur. 

The  so-called  "  ciba "  dyes  are  indigo  derivatives  con- 
taining bromine. 

As  a  rule,  cotton  goods  will  not  dye  without  previous 
treatment  with  a  mordant,  the  mordant  in  such  cases 
directly  combining  with  and  thus  fixing  the  dye  and  the 
mordants  used ;  for  acid  dyes,  feeble  bases  like  aluminic, 
chromic,  and  ferric  hydroxides  (which  are  produced  on  the 
fabrics  by  immersing  them  in  solutions  of  the  acetates  of 
these  bases  and  steaming  them)  are  used,  the  colours  of  the 
"  lakes"  so  produced  varying  with  the  base  employed.  Using 
basic  dyes  for  cotton  goods,  these  are  first  mordanted  with 


DYES  AND  DYEING— EFFLORESCENCE  161 

DYES  AND  DYEING  (Continued)— 

tannic  acid  or  a  tin  salt,  such  as  the  chloride.  (See  also 
Azo-dyes,  Flavone,  Plant  Colouring  Matters,  Rosanilines, 
and  Triphenylmethane.) 

DYNAMITE— See  Explosives. 
DYNAMO— See  Electricity. 

DYSPROSIUM  (Dy)— Atomic  weight,  162-5.  An  exceedingly 
rare  and  but  little  known  element. 

EARTH— See  Matter. 
EARTHENWARE— See  Porcelain 
EARTH-NUT  OIL— See  Arachis  Oil. 
EARTH-WAX— Ceresin.     (See  Waxes.) 

EAU  DE  COLOGNE — A  solution  of  various  essential  oils  in 
alcohol  prepared  as  a  perfume. 

EAU  DE  JAVELLE — A  dilute  solution  of  sodium  hypochlorite 
at  one  time  commonly  used  in  France  for  bleaching  and 
disinfecting  purposes.  It  can  be  prepared  by  treating  a 
solution  of  calcium  hypochlorite  with  one  of  sodium 
carbonate  and  filtering  off  the  precipitated  calcium  car- 
bonate. 

EBONITE— See  Vulcanite. 

EBONY — The  black  heart-wood  of  Diospyws  ebenum,  which 
grows  in  Ceylon,  Madagascar,  etc. 

EBULLIOSCOPE — A  form  of  apparatus  for  determining  the 
boiling-points  of  liquids. 

EBULLITION — Boiling. 

EDUCT — A  body  separated  or  brought  to  light  by  the  splitting 
up  of  a  substance  in  which  it  previously  existed  in  chemical 
association,  and  not  actually  produced  by  the  decomposition. 

EFFERVESCENCE — Escape  of  gas  from  a  liquid  or  mixture,  as, 
for  example,  when  hydrochloric  acid  is  poured  on  marble, 
carbon  dioxide  gas  is  evolved  ;  or  as,  again,  when  soda- 
water  (which  is  water  charged  under  pressure  with  the 
same  gas)  is  allowed  to  escape  from  a  siphon. 

EFFLORESCENCE— Salts  which  give  up  or  lose  a  part  of  their 
water  of  crystallization  on  exposure  to  the  air  and  thereby 
become  coated  with  a  pulverulent  deposit  due  to  this  change, 
are  described  as  efflorescent. 

ii 


162  EFFLORESCENCE— ELECTRICITY 

EFFLORESCENCE  (Continued)— 

Common  washing  soda  (Na2CO3ioH2O)  by  efflorescence 
loses  9  out  of  its  10  molecules  of  water  and  becomes 
reduced  to  the  carbonate  of  sodium  (of  different  crystalline 
form)  represented  by  the  formula  NagCO^H^O. 

EGGS  are  nutritious  articles  of  food.  The  shell  of  birds'  eggs 
consists  for  the  most  part  of  calcium  carbonate  (about  90 
per  cent.),  calcium  and  magnesium  phosphates  (about  6  per 
cent.),  and  animal  matter  and  sulphur  (about  4  to  5  per  cent.). 
The  white  of  egg  is  albumin,  whilst  the  yolk  is  of  compli- 
cated composition  containing  fatty  matters,  lecithin  (a 
phosphorized  organic  principle  present  in  brain  matter), 
cholesterine,  etc. 

The  eggs  and  roes  of  fishes  are,  for  the  most  part,  of 
somewhat  similar  composition  and  equally  valuable  as  foods. 

Both  the  albumin  and  the  yolks  of  eggs  are  used  in  many 
industries. 

ELAlDIC  ACID — A  white  crystalline  stereoisomericformof  oleic 
acid  (C18H34O2),  obtained  by  the  action  of  nitrous  acid  upon 
that  substance  at  200°  C.  in  the  presence  of  sulphurous 
acid  or  sodium  bisulphite.  It  melts  at  51°  to  52°  C. 

ELASTICITY — Capability  of  being  stretched  and  resumption 
of  original  shape  and  dimension  upon  cessation  of  the  force 
used  to  alter  the  original  form. 

ELECTRICAL  PRECIPITATION  OF  GASES— See  Cottrell 
Precipitating  Plant. 

ELECTRICITY  (and  Magnetism) — Electricity,  like  heat  and 
light,  has  in  the  past  been  generally  regarded  as  a  form  of 
energy,  often,  if  not  always,  produced  as  one  of  the  results 
or  accompaniments  of  chemical  action.  Indeed,  it  was  at 
one  time  chiefly  produced  by  chemical  means,  using  what 
are  called  voltaic  batteries  specially  constructed  for  the 
purpose. 

Sir  Joseph  Thomson  is  supposed  to  have  proved  that  the 
agency  we  call  negative  electricity  is  atomic  in  structure, 
and  exists  in  indivisible  units  now  named  electrons,  carry- 
ing a  certain  electric  charge,  having  a  certain  mass,  as 
constituents  of  all  chemical  atoms.  An  electrically  neutral 
atom  which  has  lost  one  or  more  electrons  is  called  a 
positive  ion,  and  neutral  atoms  which  have  lost  or  gained 
electrons  are  said  to  be  ionized. 

A  stick  of  sealing-wax,  a  glass  rod,  or  a  piece  of  amber 
rubbed  briskly  upon  the  coat  sleeve  becomes  electrified,  and 
in  this  state  can  be  made  to  pick  up  bits  of  paper. 


ELECTRICITY  163 

ELECTRICITY  (Continued)— 

There  are  machines  which  produce  electricity  by 
friction,  as,  for  example,  when  a  plate  of  glass  is  made 
to  revolve  rapidly  between  two  cushions  of  cloth.  An 
appliance  of  this  kind  can  be  constructed  in  connection 
with  metallic  parts  in  such  a  way  that  the  electricity  con- 
ducted to  a  point  and  discharged  therefrom  in  the  form  of 
sparks  is  strong  enough  to  knock  a  man  down. 

Lightning  is  a  discharge  of  electricity  (as  revealed  to 
the  senses  by  accompanying  light  and  sound)  from  clouds 
charged  with  it;  and  just  as  heat  can  be  conducted  by  metals, 
so  can  electricity.  It  is  for  this  reason  that  so-called 
lightning  conductors  are  attached  to  tall  buildings  and 
chimney-shafts  to  protect  them  against  destruction.  These 
lightning  conductors  are  generally  made  of  copper  with 
pointed  ends,  and  they  attract  and  conduct  the  electric  force 
into  the  earth  or  water  with  which  they  are  connected  at 
the  lower  end. 

If  two  plates  or  rods,  one  of  metallic  zinc  and  the  other 
of  metallic  copper,  be  placed  in  a  glass  jar  containing  dilute 
hydrochloric  acid  and  allowed  to  touch  each  other  or  be 
connected  by,  say,  a  piece  of  copper  wire,  a  chemical  inter- 
action is  seen  to  take  place.  The  zinc  is  attacked  by  the 
acid,  although  the  copper  appears  to  be  unaffected  ;  the 
acid  is  decomposed  and  hydrogen  gas  is  given  off  from  the 
surface  of  the  copper,  the  zinc  having  a  greater  attraction 
for  the  chlorine  of  the  hydrochloric  acid  than  the  copper. 
The  explanation,  so  far  as  it  is  understood,  is  complicated  ; 
but  it  may  be  said  that  the  two  metals  assume  opposite 
electric  states  :  a  current  of  electricity  flows  away  from  the 
zinc  and  carries  the  hydrogen  gas  to  the  copper  from  the 
surface  of  which  it  is  discharged.  The  copper  is  called 
the  positive  pole  or  anode,  and  the  zinc  the  negative  pole  or 
cathode,  and,  to  prove  that  a  current  of  electricity  is  really 
passing  from  one  to  the  other,  it  is  only  necessary,  instead 
of  allowing  the  two  plates  to  touch  each  other,  to  connect 
the  two  metals  under  these  circumstances  with  a  fine 
thread  of  platinum  wire  instead  of  one  of  copper,  when — 
because  it  is  not  such  a  good  conductor  of  electricity, 
and  therefore  offers  more  resistance  to  its  passage — it 
becomes  red-hot,  showing  that  the  electric  discharge,  being 
impeded  or  obstructed,  is  transformed  to  some  extent  into 
heat. 

Again,  if  a  strip  each  of  zinc  and  platinum  be  dipped  in 
a  vessel  containing  dilute  sulphuric  acid,  little  action  takes 
place  so  long  as  the  two  metals  do  not  touch  each  other ; 


1 64 


ELECTRIC  BATTERIES 


ELECTRICITY  (Continued)— 

but  if  they  be  joined  together  with,  say,  a  copper  wire,  the 
zinc  commences  to  dissolve  and  hydrogen  gas  is  given  off 
from  the  surface  of  the  platinum  strip,  although  that  metal 
itself  is  entirely  unaffected  by  the  acid.  Meanwhile  an 
electric  current  passes  through  the  wire,  and  continues  to 
do  so,  as  long  as  the  action  of  the  acid  upon  the  zinc  goes 
on.  This  is  another  instance  of  chemical  change  producing 
electric  energy,  and  such  an  arrangement  is  styled  a  galvanic 
or  voltaic  element.  The  wasting  of  the  zinc  furnishes  the 
energy,  and  the  quantity  of  electricity  that  passes  is  pro- 
portional to  the  amount  of  chemical  action,  which  is  repre- 
sented by  the  equation 

Zn  +  H2SO4  =  ZnSO4  +  H2. 

A  battery  consists  of  a  number  of  such  elements  or  cells 
grouped  up  together.  In  this  case,  the  zinc  plate,  or  ter- 
minal wire  connected  with  it,  is  again  the  negative  pole  of 
the  battery,  and  that  of  the  platinum  plate  from  which  the 
electric  current  starts  on  its  circuit  back  to  the  zinc  is  the 
positive  pole. 

In  the  Grove  battery,  which  is  often  used  in  chemical 
laboratories,  the  outer  cell  (made  of  glass  or  ebonite)  is 
charged^  with  dilute  sulphuric  acid  (1:7)  and  a  zinc  plate 


Grove  Battery. 

(the  surface  of  which  is  amalgamated  with  mercury  to 
moderate  the  action  of  the  acid  on  the  zinc) ;  while  in  the 
inner,  or  porous  cell,  a  thin  sheet  of  platinum,  immersed  in 
strong  nitric  acid,  serves  as  the  negative  pole.  The  zinc 
being  attacked  by  the  sulphuric  acid  liberates  hydrogen, 
which  in  passing  through  the  nitric  acid  decomposes  it, 
producing  water  and  nitric  peroxide  (N2O4)  gas. 


ELECTROLYSIS 


165 


Bunsen  Cell. 


ELECTRICITY  (Continued)— 

The  next  illustration  is  of  a  cylindrical  cell  of  Bunsen's 
carbon  battery,  consisting  of  an  oblong  prism  of  carbon,  a 
zinc  cylinder,  a  porous  pot,  glass  cell,  and  binding  clamp. 

In  this  modification  of  Grove's 
battery,  the  carbon  replaces  the 
platinum  sheet,  and  is  connected 
with  the  zinc  of  the  next  cell  by 
means  of  a  copper  strip. 

A    third    form,    which    finds 
more    general     use    and    is    of 
special  service  for  working  elec- 
tric bells  and  telephones,  is  the 
Leclanche  battery.     In  this,  zinc- 
carbon  cells  are  employed ;  that 
is  to  say,  each  cell  consists  of  a 
glass  vessel  in  which  are  placed 
a  block  or  plate  of  carbon  (char- 
coal)  and    a    block   or    rod    of 
metallic    zinc,    immersed    in    a 
solution  of   sal  ammoniac   (am- 
monium   chloride,    NH4C1)   dis- 
solved in  water.     On  connecting  the  carbon  and  zinc  parts 
with  wire,  the  cells  become  active  and  an  electric  current 
is   generated.      The   zinc,   in   dissolving,   forms   a   double 
chloride  of  zinc  and  ammonium,  and   ammonia   gas   and 
hydrogen  are  liberated  at   the   carbon  pole.     To  prevent 
so-called  polarization — that  is,  interference  caused   by  the 
accumulation  of  a  layer  of  bubbles  of  gas  on  the  carbon 
pole  (which  would  interfere  with  the  satisfactory  working 
of  the  battery) — the  carbon  block  or  plate  is  packed  inside 
a  porous  pot  with  fragments  of  carbon  and  powdered  man- 
ganese dioxide  (MnO2). 

There  is  reason  for  believing  that  thermo-electric 
currents  occur  in  a  single  homogeneous  metal — such,  for 
example,  as  mercury — and  not  merely  where  two  distinct 
metals  are  present. 

An  electric  current  is  capable  of  breaking  up  or  decom- 
posing many  chemical  substances  when  in  a  state  of  solu- 
tion, and  this  process  is  described  as  electrolysis.  For 
example,  a  moderately  strong  solution  of  hydrochloric  acid 
(HC1)  is  resolved  in  this  way  into  hydrogen  gas,  which  is 
given  off  at  one  pole,  and  chlorine  gas,  which  is  evolved  at 
the  other  pole.  Water  can  similarly  be  broken  up  into  its 
constituent  parts,  and  the  resulting  elements  are  always 
produced  in  their  equivalent  proportions  —  i  part  of 


166  ELECTRICITY  AND  MAGNETISM 

ELECTRICITY  (Continued) — 

hydrogen,  for  example,  being  accompanied  by  35^  parts 
of  chlorine  when  hydrochloric  acid  solution  is  decomposed 
as  above  referred  to.  In  the  electrolysis  of  cupric  sulphate 
solution,  the  positively  charged  copper  ions  or  electrons 
are  deposited  on  the  cathode,  and  are  termed  cathions,  while 
the  SO4  ions,  which  move  to  the  anode  and  are  negatively 
charged,  are  termed  anions.  It  is  these  charges  of  elec- 
tricity which  differentiates  ions  from  the  free  elements. 
(See  Voltameter.) 

The  electric  current  which  is  generated  by  chemical  or 
galvanic  batteries  can  be  conducted  or  carried  away  by 
metallic  wires  or  rods  in  the  form  of  a  current  and  utilized 
as  such,  or  can  be  transformed  into  heat,  as  in  electric 
radiators,  or  into  power  by  means  of  electric  motors. 

The  art  of  electro-plating  of  metals  is  dependent  upon 
the  deposition  of  metals  from  solution  on  other  metals,  as 
effected  by  the  electrolysis  of  metallic  solutions.  In  silver- 
plating,  for  example,  the  articles  to  be  plated  are  hung  in 
the  solution  of  a  silver  salt,  and  plates  of  pure  silver  are 
also  placed  in  the  same  liquid,  a  current  of  electricity  being 
passed  in  through  the  silver  plates  and  out  from  the  iron  or 
other  articles  to  be  plated.  In  this  way  the  pure  silver  is 
gradually  dissolved,  and  that  metal  is  deposited  as  a  coating 
on  the  spoons,  forks,  or  other  articles  which  it  is  desired  to 
plate. 

As  opposed  to  metals  which  are  good  conductors  of 
electricity,  other  substances  show  a  resistance  or  incapability 
of  conduction,  and  such  non-conducting  materials  are  used 
in  the  construction  of  so-called  insulators  ;  for  example,  the 
porcelain  blocks  or  cups  that  are  used  on  telegraph-posts 
for  carrying  the  electric*  wires,  so  that  the  current  is  not 
wasted  by  being  carried  or  conducted  away  from  the  wires ; 
and  for  the  same  reason  telegraph  cables  are  covered  with 
gutta-percha,  which  is  non-conducting. 

Magnetism  is  of  the  same  essential  nature  as  electricity, 
and  the  mineral  known  as  loadstone  (magnetic  oxide  of 
iron)  possesses  the  power  of  attracting  iron  as  a  natural 
property.  Steel  is  easily  magnetized  by  contact  with 
another  magnet,  and  it  then  has  the  property  of 
attracting  or  drawing  towards  its  poles  a  needle  or 
piece  of  iron  placed  near  to  it.  Nickel  and  cobalt  are 
also  magnetic.  Magnetism  acts  not  only  at  a  distance,  but 
also  through  paper  or  silk  or  glass;  that  is  to  say,  if  a 
needle  be  placed  on  a  thin  sheet  of  paper  or  glass,  a  magnet 
moved  about  under  the  paper  or  glass  attracts  and  draws 


ELECTRICITY  AND  DYNAMOS  167 

ELECTRICITY  (Continued) — 

the  needle  in  whichever  direction  it  moves.  The  whole 
earth  acts  as  a  magnet,  and  its  magnetic  poles,  although 
not  identical  with  the  geographical  poles,  are  in  their  near 
neighbourhood.  Consequently  the  mariner's  compass,  being 
a  magnetized  needle  and  placed  upon  a  pivot,  always  points 
one  end  to  the  north  and  the  other  to  the  south.  The  ease 
with  which  iron  or  steel  can  be  magnetized  by  electricity  is 
utilized,  as  we  shall  presently  show,  in  the  construction  of 
electro-magnetic  machines. 

Electric  currents  are  known  to  exist  in  the  muscles  and 
nerves  of  animal  structures,  and  are  doubtless  connected 
with  the  chemical  changes  that  are  constantly  taking  place 
in  living  bodies.  Cats  emit  electricity,  and  in  dry  frosty 
weather,  little  sparks  can  be  seen  to  pass  from  the  standing 
fur  of  their  coats  to  the  hand  when  used  for  stroking 
them. 

Several  water-animals  produce  electric  discharges,  and  in 
particular  may  be  mentioned  the  Raid  torpedo  (or  electric 
ray),  found  in  the  Mediterranean  and  Atlantic,  which 
possesses  an  electric  organ  on  the  back  of  its  head ;  whilst 
the  Gymnotus  electricus  (or  Surinam  eel)  has  an  electric 
organ  running  along  the  whole  length  of  its  body,  and  is 
capable  of  giving  a  terrible  shock. 

The  discovery  by  Faraday  that  currents  of  electricity 
can  be  induced  in  a  conductor  by  moving  it  between  the 
two  poles  of  a  magnet  has,  in  course  of  time,  led  to  the 
construction  of  the  magneto-electric  machines  known  as 
dynamos  or  electric  generators  and  electric  motors,  both  of 
which  appliances  are  now  extensively  used  for  many  com- 
mercial purposes. 

Dynamos  have,  of  course,  supplanted  the  use  of  voltaic 
batteries  in  all  cases  where  large  applications  of  electricity 
are  required. 

Dynamo-electric  machines  produce  electricity  by  the 
rapid  rotation  of  an  armature  made  of  iron  and  wound  round 
with  coils  of  insulated  wire,  between  (but  not  touching) 
the  two  poles  of  a  fixed  magnet  round  which  are  also 
wound  coils  of  insulated  wire,  it  having  been  found 
that  the  magnetism  and  consequent  electric  current  is 
intensified  by  this  wrapping  of  wire.  The  rotation  of 
the  armature,  as  it  is  called,  can  be  effected  by  using  the 
power  of  waterfalls,  or  steam,  gas,  and  oil  engines. 

The  current  of  electricity  thus  generated  flows  alternately 
in  opposite  directions  as  the  coils  pass  the  two  poles  of  the 
fixed  magnet ;  but  a  device  called  the  commutator  (placed 


168  ELECTRICITY 

ELECTRICITY  (Continued)— 

on  the  same  shaft  as  that  which  carries  the  armature)  has 
collecting  brushes  attached  to  it,  and  these  gather  up 
and  cause  the  current  to  flow  in  one  and  the  same 
direction. 

The  electric  motor  is  constructed  on  the  same  general 
principle,  but  in  this  case  the  electric  current  is  used  to 
cause  the  rotation  of  the  armature,  which  in  its  turn  is 
employed  as  a  propellant  for  the  machinery  with  which 
it  may  be  connected,  and  in  this  way  the  electricity  em- 
ployed is  converted  into  mechanical  power. 

The  electric  telegraph  enables  the  user  to  transmit  signals 
by  means  of  an  electric  current  to  distant  places,  the  move- 
ments or  sounds  made  at  one  end  of  the  wire  being  repro- 
duced at  the  other  end.  These  movements  or  sounds  are 
interpreted  by  an  understood  code,  and  in  some  cases  the 
messages  are  printed  in  type  or  ordinary  letters. 

The  telephone  is  another  electric  contrivance  by  means  of 
which  an  electric  current  passing  through  or  along  a  wire 
reproduces  at  the  far  end,  or  receiver,  movements  corre- 
sponding to  those  produced  in  the  transmitter  by  the  sound 
waves  of  the  voice. 

Electric  lights  are  of  two  classes — viz.,  the  arc  light  and 
the  incandescent  light.  In  the  former,  the  electric  current 
passes  from  an  upper  rod  of  carbon  to  a  lower  one  across 
the  space  which  is  maintained  between  them,  producing  a 
cloud  of  carbon  vapour  which,  being  intensely  heated,  forms 
a  luminous  arc  of  flame  or  light.  In  incandescent  lamps, 
on  the  other  hand,  the  filament  or  thread  of  carbon  or 
metal  which  is  made  luminous,  is  contained  within  a  glass 
vessel  from  which  the  air  has  been  removed.  If  these 
lamps  were  not  exhausted  of  air,  carbon  threads  would 
be  destroyed  by  burning — that  is,  by  combination  of  the 
carbon  with  the  oxygen  contained  in  the  air.  As  it  is,  the 
current  flows  in  at  one  end  of  the  filament  and  out  at  the 
other  and  heats  it  to  a  state  of  incandescence.  In  other 
words,  so  much  of  the  electric  current  is  transformed  into 
heat  and  light  in  consequence  of  the  resistance  offered  to 
its  passage.  To  a  very  large  extent,  carbon  filaments  are 
no  longer  used,  metallic  ones  of  various  kinds  having 
replaced  them  to  great  advantage. 

The  so-called  storage  batteries  do  not  really  store  up  the 
electric  current  which  is  passed  into  them.  The  current 
used  for  charging  them,  effects  certain  chemical  changes 
or  decompositions  in  the  contents  of  the  storage  cells, 
and  these  changes  are  of  such  a  character  that  when 


ELECTRICITY— ELECTROLYSIS  169 

ELECTRICITY  (Continued)— 

the  electric  current  is  shut  off,  the  storage  cells  act  as 
voltaic  batteries  in  consequence  of  further  new  chemical 
changes  that  then  take  place.  In  other  words,  when  they 
are  used,  they  run  down  or  undo  the  changes  effected  by 
the  electric  charge  and  restore  the  elements  of  these  cells 
to  their  original  condition,  thus  preparing  them  ready  to 
receive  a  further  charge  of  electricity. 

Electrolytic  methods  are  now  largely  used  in  the  manu- 
facture of  various  chemicals,  being  employed,  for  example, 
in  the  preparation  of  the  metals  sodium,  magnesium, 
calcium,  and  aluminium  by  the  electrolysis  of  fused  com- 
pounds of  these  metals ;  also  for  refining  copper,  silver, 
and  gold  ;  the  extraction  of  some  metals  from  their  solu- 
tions, the  manufacture  of  soda,  and  the  preparation  of 
hydrogen  and  oxygen  gases. 

The  introduction  of  the  dynamo  has  also  led  to  the  con- 
struction of  electrical  furnaces,  one  of  which,  constructed 
on  the  principle  of  the  arc  light,  exhibits  a  temperature  of 
from  about  3,000  to  3,500°  C.  They  are  used  amongst 
other  applications  for  the  production  of  carborundum, 
graphite,  artificial  sapphires,  rubies,  calcium  carbide  (CaC2), 
silicon,  fused  silica  ware  for  chemical  use,  the  utilization  of 
steel  turnings,  the  remelting  of  nickel-chrome  steel,  the 
preparation  of  ferro-alloys,  etc. 

Electric  furnaces,  in  which  the  heating  element  consists 
of  a  metallic  wire  or  strip,  are  now  widely  used  in  labora- 
tories and  workshops,  and  there  are  a  variety  of  specially 
constructed  ones  made  on  the  "  muffle "  and  other  prin- 
ciples. 


ELECTRIC  BATTERIES— } 
FURNACE 
LAMPS 
LIGHT 
MOTORS 
RADIATORS 
TELEGRAPH 
TELEPHONE 


See  Electricity. 


ELECTRODES— The  poles  of  an  electric  battery  or  the 
terminals  carrying  an  electric  current  into  and  out  from  a 
liquid. 

ELECTROLYSIS— Decomposition  of  fluids  by  the  agency  of 
the  electric  or  voltaic  current. 


i;o  ELECTROLYTE— ELEMENTS 

ELECTROLYTE— A  substance  admitting  of  being  broken  up 
by  electrolysis. 

ELECTRO-GILDING— See  Gold. 
ELECTRO-PLATING— See  Electricity. 

ELECTRONS — Hypothetical  conceptions  of  ultra-atomic  par- 
ticles or  corpuscles,  carrying  a  negative  charge  of  elec- 
tricity, this  charge  being  the  smallest  known ;  it  being 
further  supposed  that  every  quantity  of  electricity  is  a 
multiple  of  this  elementary  charge,  and  that  these  electrons 
are  incomparably  smaller  than  atoms.  The  mass  of  the 
electron  is  said  to  be  1,830  times  smaller  than  the  atom 
of  hydrogen,  which  is  the  lightest  known ;  but  from  a 
chemical  point  of  view,  electrons  must  be  constituent  parts 
of  atomic  matter.  The  number  of  electrons  in  an  atom  is 
stated  to  be  approximately  half  its  atomic  weight.  The 
term  is  used  more  generally  to  characterize  the  extremely 
minute  particles  shot  off  in  electric  discharges  in  gases,  as 
well  as  the  emissions  from  helium,  argon,  and  other  radio- 
active substances.  (See  Atoms,  Cathode  Rays,  Rontgen 
Rays,  and  Radio-activity.) 

ELEMENTS— The  various  forms  of  matter  of  which  all 
chemical  combinations  are  composed.  They  are  only  to  be 
regarded  as  elemental  in  the  sense  that  they  cannot  be 
easily  decomposed  or  split  up  into  two  or  more  distinct 
substances.  Gold  is  an  example,  and  from  it  substantially 
nothing  but  gold  can  be  obtained,  as  distinct  from  a  com- 
pound body  like  water  which  can  be  decomposed  into 
hydrogen  and  oxygen. 

It  is,  however,  conceivable,  and  believed  by  many,  that 
all  the  elements  are  really  compounded  of  one  primordial 
matter  (protyle),  and  only  vary  in  character  according  to 
the  physical  conditions  under  which  they  exist  and  are 
recognized.  Eighty-three  or  more  of  these  entities  are 
known,  and  there  are  probably  more  yet  undiscovered. 

Most  of  these  entities  are  metallic  in  character,  but  the 
non-metallic  ones  exist  more  abundantly  in  nature,  and  in- 
clude oxygen,  silicon,  hydrogen,  nitrogen,  carbon,  chlorine, 
bromine,  fluorine,  and  iodine.  The  two  classes  of  metallic 
and  non-metallic  bodies  gradually  merge  into  one  another, 
the  intermediate  class  being  sometimes  described  as 
metalloids — arsenic,  for  example. 

In  the  abbreviated  table  given  on  p.  172  the  metallic 
ones  are  marked  with  m,  while  those  marked  g  exist  ordin- 
arily in  the  gaseous  form.  A  more  complete  list  of  the 
chemical  elements  will  be  found  on  p.  44,  and  all  (and 


ELEMENTS  171 

ELEMENTS  (Continued) — 

some  of  their  compounds)  are  described  under  their  several 
names. 

The  symbols  used  to  represent  the  chemical  elements  are 
for  the  most  part  abbreviations  of  their  common  names ; 
thus,  the  symbol  of  hydrogen  is  H,  that  of  nitrogen  N, 
that  of  calcium  Ca  ;  but  there  are  exceptions,  and  while  it 
is  a  pity  that  the  symbols  of  these  exceptional  instances 
are  still  used,  it  will  be  useful  to  explain  the  reason. 

The  metal  antimony  has  the  symbol  Sb  because  the 
Latin  name  for  antimony  is  stibium. 

The  metal  lead  has  the  symbol  Pb,  the  Latin  name  for 
lead  being  plumbum. 

The  metal  mercury  is  indicated  by  the  letters  Hg,  as  the 
Latin  name  for  it  is  hydrargyrum. 

Potassium  is  symbolized  by  the  letter  K,  its  Latin 
name  being  kalium. 

Sodium  is  symbolized  by  Na  because  natrium  is  its  Latin 
name. 

The  metal  tin  has  the  symbol  Sn,  from  the  Latin  name 
st  annum. 

The  metal  gold  is  marked  Au,  from  the  Latin  name  aurum. 

The  metal  iron  is  marked  Fe,  from  the  Latin  nameferrum. 

The  metal  silver  is  marked  Ag,  from  the  Latin  name 
argentum. 

The  metal  copper  is  marked  Cu,  from  the  Latin  name 
cuprum. 

The  chemical  constitution  of  compounds  is  represented 
by  so-called  formula  or  combinations  of  letters  or  symbols  ; 
thus,  the  formula  of  common  salt  (sodium  chloride)  is 
NaCl,  that  of  water  H2O,  and  so  forth.  (See  Formulas.) 

Classification  of  the  Elements — The  chief  elements  can, 
to  some  extent  at  least,  be  classified  into  natural  groups  in 
respect  of  their  resemblances — viz.,  as  follows  : 

1 .  A  Ikali  metals,  including  potassium,  sodium,  and  lithium. 

2.  So-called    alkaline  -  earth    metals,    including    barium, 
strontium,  calcium,  and  magnesium. 

3.  Halogens,   including    chlorine,    bromine,    iodine,    and 
fluorine. 

4.  A  larger  group   may  be  defined  as  more  definitely 
metallic  than  those  referred  to  in  classes  i  and  2,  and  in- 
clude aluminium,  antimony,  bismuth,  cadmium,  chromium, 
cobalt,  copper,  gold,  iron,   lead,  magnesium,   manganese, 
mercury,  nickel,  platinum,  silver,  tin,  vanadium,  and  zinc. 

5.  Those  which  are  better  known  in  their  gaseous  state  are : 
hydrogen,  chlorine,  fluorine,  oxygen,  nitrogen,  and  argon. 


172 


ELEMENTS  AND  THEIR  SYMBOLS 


ELEMENTS  (Continued)— 

6.  The  non-metals  include  all  the  elements  in  classes  3  and 
5,  also  boron,  sulphur,  carbon,  phosphorus,  and  silicon. 

Carbon  is  peculiar  as  being  the  one  essential  element  of 
all  so-called  organic  compounds,  whilst  silicon  is  one  of  the 
most  abundant  elements  found  in  nature.  Apart  from  the 
carbonates  of  the  metals,  most  of  the  other  compounds  con- 
taining carbon  are  known  as  organic  compounds,  and,  indeed, 
organic  chemistry  is  sometimes  defined  as  the  chemistry 
of  carbon  and  its  compounds.  These  compounds  are  more 
numerous  than  those  of  all  the  other  elements,  and  so  far 
as  they  are  constituents  of  animal  and  vegetable  tissues, 
they  are  of  more  complicated  constitution  than  most  other 
chemical  compounds :  besides  oxygen  and  hydrogen,  they 
not  infrequently  include  nitrogen,  sulphur,  and  phosphorus 
as  constituents. 

Better  Known  Elements — 

LlST,     WITH      THEIR      SYMBOLS      AND      GENERALLY      ACCEPTED 

ATOMIC  WEIGHTS,  HYDROGEN  (i)  BEING  TAKEN  AS  THE 
STANDARD. 


Name. 

Symbol. 

Atomic 
Weight. 

Name. 

Symbol 

Atomic 
Weight. 

m  Aluminium 

Al 

27 

m  Magnesium 

Mg 

24 

m  Antimony 

Sb 

120 

m  Manganese 

Mn 

55 

m  Arsenic 

As 

75 

m  Mercury 

Hg 

200 

m  Barium 

Ba 

137 

m  Nickel 

Ni 

59 

m  Bismuth 

Bi 

208 

g  Nitrogen 

N 

14 

Boron 

B 

ii 

g  Oxygen 

0 

16 

Bromine 

Br 

80 

Phosphorus 

P 

3i 

m  Cadmium 

Cd 

112 

m  Platinum           Pt 

195 

m  Calcium 

Ca 

40 

m  Potassium 

K 

39 

Carbon 

C 

.12 

m  Radium 

Ra 

226-4 

g  Chlorine 

Cl 

35*5 

Silicon 

Si 

28 

m  Chromium 

Cr 

52 

m  Silver            1    Ag 

108 

m  Cobalt 

Co 

59 

m  Sodium 

Na 

23 

m  Copper 

Cu 

63-5 

m  Strontium 

Sr 

87-6 

g  Fluorine 

Fl 

19 

Sulphur 

S 

32 

wGold 

Au 

197 

m  Thorium 

Th 

232 

g  Hydrogen 

H 

i 

m  Tin 

Sn 

118 

Iodine 

I 

127 

m  Uranium 

U 

238-5 

m  Iron 

Fe 

56 

m  Vanadium 

V 

5i 

m  Lead 

Pb 

207 

m  Zinc 

Zn 

65 

m  Lithium 

Li 

7 

ELEMENTS— PERIODIC  LAW  i?3 

ELEMENTS  (Continued)— 

Periodic  Law — Many  of  the  chemical  elements  that  re- 
semble one  another  in  their  properties  appear  also  to  exhibit 
certain  numerical  relations — for  example,  lithium,  sodium, 
and  potassium  having  the  atomic  weights  of  7,  23,  and  39 
exhibit  an  average  number  23  by  the  addition  of  the  two 
extreme  numbers,  7  and  39,  and  dividing  by  2,  this  average 
being  that  of  the  atomic  weight  of  sodium.  These 
numerical  relations  and  the  gradation  in  the  properties 
of  the  elements  have  led  up  to  what  is  known  as  the 
periodic  law,  the  basic  idea  being  that  the  chemically 
analogous  elements  constitute  families,  the  members  of 
which  recur  after  regular  intervals  when  arranged  in  order 
of  their  atomic  weights.  It  may  be  broadly  expressed  by 
the  statement  that  the  properties  of  the  elements  and  their 
compounds  constitute  a  periodic  function  of  the  elemental 
atomic  weights.  These  functions  are  noticeable,  fpr  example, 
in  their  electrical  characters,  the  ductility,  malleability,  and 
melting-points  of  the  metals,  and  in  their  so-called  atomic 
volumes.  The  full  meaning  of  these  relations  is  not  yet 
clear,  but  as  a  working  hypothesis  the  periodic  law  has 
proved  of  much  service,  and  further  investigations  will, 
without  doubt,  clear  up  much  that  is  at  present  not  under- 
standable regarding  the  constitution  of  the  entities  of 
matter  as  presented  in  the  various  so-called  elements  and 
their  multitudinous  compounds. 

If  the  atomic  weights  of  two  elements  be  divided  by 
their  respective  specific  gravities  the  quotients  give  the 
relative  volumes  occupied  by  their  respective  single  atoms, 
and  Hawksworth  Collins  concludes  from  this  and  other 
considerations  that  "  the  relative  volumes  of  the  elements 
are  the  fundamental  constants  of  nature." 

Evidence  has  been  adduced  to  indicate  that  cohesiveness 
as  well  as  chemical  affinity,  exerts  pressure  in  its  action 
and  plays  a  part  in  determining  the  volumes  occupied  by 
molecules. 

Richards  has  pointed  out  that  the  compressibilities  of  the 
solid  elements  as  determined  by  him  at  Harvard  University 
seem  to  be,  like  the  atomic  volumes,  periodic  functions  of 
the  atomic  weights. 

As  to  the  transmutation  of  the  elements  it  has  been  con- 
jectured that  the  following  cases  may  possibly  be  factual : 

Radium  —     Helium  =  Niton 

(226  atomic  weight)  (4)  (222) 

4  Hydrogen  =  Helium 

(4)  (4) 


174  ELEMENTS— CHEMICAL  ENTITIES 

ELEMENTS  (Continued)— 

4  Hydrogen  +     Oxygen  =Neon 

(4)  (16)  (20) 

Sulphur  +  8  Hydrogen  =  Argon 

(32)  (8)  (40) 

Selenium  +  4  Hydrogen  =  Krypton 

(79)  (4)  (83) 

(Compare  Radio-activity,  Electrons,  Radium,  and  Atoms. ) 

A  modified  (isotypic)  form  of  metallic  lead  can  be 
apparently  derived  from  uranium  through  ionium  and 
radium  as  intervening  atomic  matters,  although  this  calls 
for  definite  confirmation.  (See  Lead.) 

The  origination  of  helium  from  uranium  and  thorium- 
bearing  minerals;  its  production  from  radium  and  niton 
established  qualitatively  and  quantitatively ;  and  lastly  its 
synthesis  by  subjecting  hydrogen  to  the  action  of  the 
cathode  "rays  and  its  combination  with  oxygen  to  produce 
neon :  all  these  circumstances  seem  to  demonstrate  trans- 
mutations of  the  chemical  elements  and  the  common  basic 
nature  of  ultimate  matter. 

According  to  Dr.  Aston,  who  has  employed  a  method  of 
so-called  "mass  spectra"  (that  is,  spectra  obtained  on  a 
photographic  plate  placed  in  vacuo,  by  deflecting  positive 
rays  on  to  it  by  passing  them  first  through  an  electric  and 
then  through  a  magnetic  field  in  such  a  way  that  all  the 
rays  corresponding  to  an  element  of  given  mass  are  con- 
centrated in  a  short  line,  on  the  plate  and  those  of  different 
masses  in  other  parallel  lines),  it  has  been  demonstrated 
that  boron  consists  of  two,  neon,  silicon,  and  chlorine  of 
two  or  three,  bromine  of  two,  krypton  of  six,  and  mercury 
of  at  least  two  isotypes— that  is,  elements  of  the  same 
chemical  properties  but  of  different  atomic  weights.  (See 
Isotypes.) 

Some  writers  on  this  particular  subject  regard  it  as  proved 
that  all  the  elements  are  polymers  of  hydrogen.  In  view, 
however,  of  recent  investigations  concerning  atomic  struc- 
ture, radio-activity,  and  the  facts  above  and  elsewhere 
referred  to,  it  appears  hardly  correct  to  write  any  longer  of 
chemical  elements,  but  to  regard  them  merely  as  more  or  less 
stable  chemical  entities,  recognizable  by  their  physical  and 
chemical  characteristics  under  particular  circumstances,  but 
susceptible  of  an  indefinite  number  of  changes  capable 
of  being  brought  about  by  the  disturbing  influence  of 
applied  force.  There  is  an  interdependence  of  matter  and 
force,  and  just  as  the  manifestations  of  heat,  light,  and 


ELEMENTS— EMULSION  175 

ELEMENTS  (Continued)— 

electricity  cannot  be  made  without  the  employment  of 
chemical  entities,  so  also  these  chemical  entities  depend  for 
their  characteristics  and  changes  upon  force :  no  matter 
without  force,  no  force  without  matter.  In  other  words, 
chemical  substances  may  be  regarded  as  symmetrical 
arrangements  of  matter.  (See  Electrons.) 

ELEMI — See  Gums. 

ELUTRIATION — Separation  of  the  lighter  from  the  heavier,  or 
smaller  from  the  larger  particles  of  powders  by  washing 
and  decantation  by  means  of  an  appliance  known  as  an 
"  elutriator  "  as  used  in  the  preparation  of  ground  barytes 
for  making  paint. 

EMBOLITE — A  mineral  chloro-bromide  of  silver  found  in 
Arizona,  Colorado,  New  Mexico,  and  Chile,  having  the 
composition  Ag5Cl3Br2  or  Ag(ClBr). 

EMERALD — A  double  silicate  of  aluminium  and  glucinum,  or 
green  variety  of  beryl,  being  a  gem  found  in  mineral  form. 

EMERALD  GREEN — A  pigment,  being  a  combination  of  metar- 
senite  and  acetate  of  copper  (3Cu(AsO2)2,(Cu)C2H3O2)2). 

EMERY — A  native  form  of  alumina  coloured  with  oxides  of 
iron  and  manganese  (corundum)  ;  used  as  an  abrasive — that 
is,  for  grinding  and  polishing — by  reason  of  its  hardness. 

EMETINE — A  mixture  of  alkaloids  extracted  from  the  root  of 
Cephaelis  ipecacuanha,  which,  as  also  their  hydrochlorides,  is 
largely  used  in  medicine  and  dentistry. 

EMULSIN  (Synaptase) — An  enzyme  being  a  constituent  of 
bitter  almonds  capable  of  hydrolyzing  most  of  the  natural 
glucosides.  (See  Amygdalin  and  Glucosides.) 

EMULSION — A  mechanical  admixture  of  fluids  that  will  not 
naturally  mix  together,  such  as  oil  and  water.  Emulsions 
are  apt  to  separate  more  or  less  into  layers  on  standing. 

Some  are  prepared  by  the  use  of  gum  or  resin  in  a  state 
of  solution  which  has  the  property  of  holding  in  suspension 
the  oily  particles  of  other  liquids  shaken  up  therewith ; 
others  are  prepared  with  milk,  the  yolk  of  eggs,  soap,  or 
mucilage.  Emulsions  are,  for  the  most  part,  milky  in 
appearance,  but  there  are  other  emulsions  which,  though 
quite  transparent  and  uniform  in  character,  are  not  to  be 
regarded  as  true  solutions. 

Emulsions  have  been  recently  described  as  "  model  sus- 
pension colloids,"  and  again  as  "  heterogeneous  systems"  in 


i?6  EMULSION— ENFLE  URA  GE 

EMULSION  (Continued)— 

which  a  liquid  is  dispersed  as  droplets  in  some  other  liquid 
with  which  it  is  only  partially  or  not  at  all  miscible. 

An  emulsion  of  oil  in  water  is  produced  if  the  emulsifying 
agent  is  a  colloid  soluble  in  water  or  more  easily  wetted 
by  water  than  oil,  and  an  emulsion  of  water  in  oil  is  obtained 
when  the  emulsifying  agent  is  an  oil-soluble  colloid  or  is 
more  easily  wetted  by  oil  than  by  water. 

ENAMELS  are  fusible  glasses  rendered  opaque  by  dissemination 
throughout  the  mass  of  a  vitreous  substance  infusible  at 
the  temperature  at  which  they  are  made,  such  as  oxide  of 
tin.  Up  to  about  900°  C.  the  tin  dioxide  exists  in  a  state 
of  suspension  in  the  enamel,  but  if  that  temperature  be 
exceeded,  real  solution  takes  place  and  the  opacity  is 
diminished.  Titanic  oxide,  zirconia,  and  other  vitreous 
substances  can  be  employed  in  place  of  the  stannic  oxide. 

The  opacity  is  due  to  the  difference  in  refractive  index, 
and  is  obtained  in  some  cases  by  the  use  of  arsenious  oxide, 
calcium  phosphate,  cryolite,  etc. 

Platinum  and  iridium  oxide  are  sometimes  used  to 
produce  greys  in  enamels,  and  a  great  variety  of  other 
substances  can  be  used  according  to  the  desired  tint  and 
other  characteristics. 

One  kind  of  enamel  used  for  glazing  cast-iron  articles, 
such  as  saucepans,  consists  of  powdered  flints  ground 
together  with  calcined  borax,  fire-clay,  and  a  little  felspar, 
made  into  a  paste  and  applied  to  the  surfaces,  which  are 
then  dusted  over  with  a  glaze-mixture  composed  of  felspar, 
soda-ash,  borax,  and  a  little  oxide  of  tin,  after  which  they 
are  dried  and  fired  at  a  red  heat. 

ENAMELLED  IRON — Iron  plates  are  enamelled  by  coating 
them,  after  cleaning,  with  alkaline  silicates  containing 
borates,  and  then  firing  them. 

ENAMEL  PAINTS — Paints  ready  mixed  with  varnish  so  that 
they  dry  with  an  enamelled  face  or  gloss.  (See  Paints.) 

ENDOSMOSE — The  passage  by  diffusion  through  a  separating 
membrane  such  as  bladder,  of  two  solutions  (one  within  the 
bladder  and  one  without  in  a  containing  vessel)  from  the 
one  into  the  other  mutually.  (See  Dialysis  and  Osmosis.) 

ENDOTHERMIC  COMPOUNDS— See  Heat. 
ENERGY — The  power  of  doing  work.     (See  Force.) 
ENFLEURAGE— See  Perfumes, 


ENZYMES  177 

ENZYMES  —  A  class  of  non-organized  colloidal  nitrogenous 
substances  produced  by  and  associated  with  certain  living 
animal  and  vegetable  tissues,  capable  of  initiating  changes 
in  many  chemical  substances  in  the  nature  of  fermentation, 
hydrolysis,  and  oxidation,  but  none  of  which  have  been 
isolated  in  a  pure  state,  their  existence  being  recognized  by 
their  actions  in  solution.  Ptyalin,  the  active  ferment  of 
saliva,  for  instance,  converts  the  starch  of  food  into  sugar. 
The  alcoholic  fermentation  of  sugar  is  due  to  the  enzyme 
named  zymase,  as  produced  by  yeast  cells.  (See  Fermen- 
tation.) For  the  most  part,  they  seem  to  act  as  catalysts 
by  way  of  hydrolysis  ;  one  such  change,  for  example,  being 
the  conversion  of  cane-sugar  into  glucose  and  fructose  by 
invertase,  brought  about  by  the  assimilation  of  water  — 

C12H22On  +  H20  =  C6H1206  +  C6H1206, 

and  another  such  change  being  the  hydrolysis  of  starch  by 
means  of  amylopsin  or  pancreatic  diastase  into  maltose  and 
dextrin,  and  by  a  further  change  these  two  saccharoid 
bodies  are  converted  into  alcohol  — 


Starch  is  similarly  converted  by  diastase  into  maltose 
(C12H22On+H2O)  (malt  sugar),  and  dextrin  is  converted 
by  the  enzyme  diastase  contained  in  germinated  barley. 

Emulsin  probably  contains  several  distinct  enzymes. 

The  digestive  enzymes  comprise  many  hydrolytic  agents 
capable  of  replacing  the  -  NH2  group  by  the  -  OH  group, 
as  in  the  case  of  urea. 

Trypsin,  one  of  the  pancreatic  enzymes,  is  most  active 
in  the  presence  of  alkalies,  and  decomposes  many  albu- 
minous bodies  down  to  the  stage  of  polypeptides,  whilst 
papain  (papayotin),  which  occurs  in  the  melon-tree  (Cavica 
papaya  L.),  is  a  similar  enzyme  of  vegetable  origin.  Pepsin, 
on  the  other  hand,  acts  only  in  acid  solutions,  and  while  it 
does  not  hydrolyze  any  known  polypeptide  it  converts 
albumins  into  a  number  of  derived  compounds  —  viz.,  the 
so-called  anti-  and  hemi-albumoses,  but  does  not  proceed 
so  far  in  its  action  as  to  produce  simple  amino  -acids. 

It  has  been  shown,  however,  that  pancreatin  and  trypsin 
can  carry  the  stage  of  hydrolysis  of  albumoses  farther, 
thus  converting  anti-albumose  into  peptone  and  hemi- 
albumose  into  leucine,  tyrosine,  aspartic  acid  and  glutamic 
acid,  these  last-named  substances  being  members  of  the 
amino-acid  group.  (See  Amino  acids  and  Proteins.) 

12 


i;8  ENZYMES 

ENZYMES  (Continued)— 

Yet  another  class  of  enzymes,  styled  desamidases,  are 
stated  to  be  capable  of  splitting  up  the  amino-acids  into 
ammonia  and  hydroxy-acids. 

Lipase,  an  enzyme  associated  with  trypsin,  has  the 
power  of  breaking  up  fats  into  glycerol  and  fatty  acids. 

There  are  certain  enzymes  occurring  in  all  parts  of 
plants  and  animals  named  oxidases,  or  ptroxidases,  which 
are  concerned  in  acts  of  oxidation,  as,  for  example,  in  the 
process  of  respiration. 

Another  enzyme,  styled  aldehydase,  said  to  be  contained 
in  the  liver,  lung,  and  spleen,  is  credited  with  the  capability 
of  converting  aldehydes  into  the  corresponding  acids. 

The  coagulase  class  of  enzymes  can  institute  changes  in 
various  liquids,  resulting  in  the  formation  of  insoluble 
substances ;  thus,  rennet  (chymase)  forms  curd  in  milk  ; 
thrombose  is  concerned  in  the  coagulation  of  blood,  and 
pectase  in  the  production  of  insoluble  pectic  acids  from  the 
pectin  substance  of  plants. 

The  particular  enzymes  associated  with  bacterial  life  are 
necessarily  many  in  number,  and  must  vary  in  their 
chemical  actions,  not  merely  with  the  kind  of  bacteria,  but 
more  particularly  with  the  media  in  which  they  are  allowed 
to  develop,  so  that  their  entire  range  of  action  must  be 
enormous  and  extremely  varied  in  character. 

In  their  action  as  catalysts,  the  rate  is  proportional  to  the 
strength  of  the  enzymes,  although  the  total  changes  which 
they  institute  are  independent  of  the  amount,  given  sufficient 
time,  and  always  provided  the  enzymes  are  not  destroyed. 
Their  activity  is  wholly  destroyed  when  heated  to  100°  C., 
while  rennet,  thrombin,  pepsin,  and  diastase  are  inactivated 
at  45°  C. 

As  to  the  mechanism  of  enzyme  action,  it  is  generally 
held  that  adsorption  compounds  (see  Adsorption)  are  formed 
between  the  enzyme  and  the  substrate — that  is,  the  sub- 
stance which  is  decomposed — and  that  it  is  these  com- 
pounds which  react  with  water  ;  but  the  whole  subject 
calls  for  much  further  investigation  before  it  can  be  fully 
understood  and  explained. 

The  action  of  enzymes  is  often  assisted  or  promoted  by 
associated  substances  styled  activators,  and,  on  the  other 
hand,  it  is  often  interfered  with  or  arrested  by  other  sub- 
stances classed  as  paralyzers,  or  poisons  (like  sulphur),  the 
latter  behaving,  in  this  sense,  as  antiseptics  do  in  respect  of 
bacterial  processes  of  decomposition.  (See  also  Catalytic, 
Emulsin,  Oxydases,  and  Vitamines.) 


EOSIN—ERBIUM  179 

EOSIN  (C20H8Br4O5)— A  red,  crystalline  dye,  soluble  in  alcohol 
and  acetic  acid,  prepared  by  the  bromination  of  fluorescein  ; 
it  is  used  for  dyeing  silk,  cotton,  and  wool ;  also  for  making 
a  red  ink.  The  potassium  salt,  C20H6Br4O5K2,  is  also 
known  commercially  as  eosin,  and  used  for  the  same 
purposes. 

"  EPHOS  " — A  basic  phosphate  made  from  an  Egyptian  source, 
containing  from  60  to  65  per  cent,  of  tricalcium  phosphate, 
of  which  85  to  95  per  cent,  is  soluble  in  0-2  per  cent, 
solution  of  citric  acid. 

"  EPONITE  "—A  decolourizing  char  in  the  nature  of  a  vege- 
table soot,  containing  about  82  per  cent,  of  carbon,  the 
decolourizing  efficiency  of  which  is  increased,  according  to 
C.  F.  Bardos,  by  addition  of  30  to  50  per  cent,  of  charred 
sawdust.  (See  "  Karbos.") 

EPSOM  SALTS— Magnesium  sulphate  (MgSO4,7H2O). 
EQUATIONS — See  Chemical  Interactions. 

EQUIVALENTS — Otherwise  described  as  "equivalent  weights" 
or  "  combining  proportions,"  represent  the  proportions 
by  weight  in  which  the  chemical  elements  combine 
amongst  themselves  ;  or,  in  other  words,  the  weights  which 
will  combine  with  i  part  of  hydrogen.  In  many  cases, 
these  equivalent  weights  are  identical  with  the  atomic 
weights  of  the  same  elements,  but  not  in  all  cases.  For 
instance,  the  affinity  of  oxygen  for  hydrogen  requires  2  atoms 
for  its  saturation  to  produce  water  (H2O),  and  as  the  relative 
weight  of  hydrogen  as  the  standard  is  i,  that  of  oxygen  is  8. 
Sulphur  also  requires  2  atoms  of  hydrogen  to  satisfy  its 
affinity,  and  whilst  its  atomic  weight  is  32,  its  equivalent 
weight  is  therefore  16.  Phosphorus  and  arsenic  require 
each  3  atoms  of  hydrogen,  and  this  varying  power  of  com- 
bination of  each  element  is  termed  its  valency.  (See 
Chemical  Compounds  and  Valencies.) 

ERBIUM  (Er) — Atomic  weight,  167-7.  A  rare  element  belong- 
ing to  the  so-called  yttrium  group,  and  occurring  in  nature 
in  the  minerals  gadolinite,  yttvotantalite,  euxenite,  etc.,  together 
with  the  earth  yttria.  Its  oxide  erbia  (Er2O3)  is  obtained 
by  heating  the  nitrate  or  precipitated  hydrate,  and  is  yellow 
in  colour,  while  its  salts,  including  the  chloride  (ErCl3), 
•  nitrate  (Er(NO3)35H2O),  bromide  (ErBr3,9H2O),  chlorate 
(Er(ClO3)3,8H2O),  bromate  (Er(BrO3)3),  and  sulphate 
(Er2(SO4)3,8H2O),  etc.,  are  crystalline  in  character,  of 
a  rosy  tint,  and  are  soluble  in  water.  The  oxide  can  be 
also  prepared  by  heating  the  oxalate  at  575°  to  845°  C. 


i8o  EREMACAUSIS— ESSENTIAL  OILS 

EREMACAUSIS — The  slow  combustion  or  consumption  by 
oxidation  and  other  changes  as  evidenced  in  nature  by  the 
decay  of  timber,  the  heating  of  grain  or  grass,  the  decom- 
position of  vegetable  matter  generally,  etc.  Low  forms  of 
life  have  much  to  do  with  the  initiation  of  the  process, 
which  is  stopped  by  perfect  dryness  and  by  a  temperature 
below  freezing-point.  (See  Dry-rot.) 

ERGOT  OF  RYE — A  fungoid  growth  on  the  seeds  of  the  com- 
mon rye,  containing  an  active  principle  named  ergotine,  in 
the  nature  of  a  yellow  crystalline  alkaloid  soluble  in  alcohol 
and  ether,  which  possesses  narcotic  properties,  and  is  used 
in  medicine.  The  formula  C35H40N4O6  is  sometimes 
assigned  to  it. 

ERLENMEYER  FLASK— See  Flasks. 

ERYTHRITE  (Cobalt  Bloom)— See  Cobalt. 

ERYTHROSIN — A  well-known  dye,  allied  in  constitution  to 
eosin. 

ESERINE  SULPHATE— An  alkaloidal  salt  made  from  the 
Calabar  bean  or  seed  of  Physostigma  venenosum  of  West 
Africa. 

ESPARTO  GRASS  (Alva)— A  strong  tufty  wild  grass  (Stipa 
tenacissima)  which  grows  abundantly  in  Spain  and  Algeria, 
and  is  largely  used  in  the  manufacture  of  cordage  and 
paper.  It  is  boiled  with  caustic  soda  to  dissolve  the 
fleshy  parts,  then  bleached.  A  wax,  amounting  to  3^  per 
cent.,  is  obtained  as  a  by-product.  The  trade  is  very  large, 
amounting  to  more  than  200,000  tons  per  annum. 

ESSENCES — Another  name  for  essential  oils. 

ESSENTIAL  OILS  are  the  volatile  oils  or  essences  formed 
naturally  in  various  trees  and  plants,  such  as  oil  of  turpen- 
tine (pine-trees),  eucalyptus  oil  (eilcalyptus-trees),  camphor 
oil  (camphor-trees),  etc. 

Many  of  them,  including  those  already  named,  are  in  the 
main  hydrocarbons,  and  are  characterized  by  their  various 
constituent  terpenes,  which  are  isomeric  bodies  having 
the  general  chemical  formula  C10H16.  Others  contain  in 
addition  oxidized  substances  of  the  nature  of  alcohols  or 
ketones  and  some  small  quantities  of  sulphur  or  nitrogen. 
Pine  and  fir  trees  are  widely  distributed  in  nature,  and  the 
turpentine  oil  which  they  yield  is  by  no  means  uniform 
in  constitution.  Russian,  American,  German,  Venetian, 
Swiss,  Swedish,  French,  and  Indian  oils  all  differ  in  the 
nature  or  proportions  of  the  various  terpenes  contained  in 
them  and  their  other  constituents. 


ESSENTIAL  OILS  181 

ESSENTIAL  OILS  (Continued)— 

The  essential  oils  have  characteristic  odours  and  are 
all  inflammable,  insoluble  in  water,  but  soluble  in  alcohol 
and  in  ether.  Many  are  more  or  less  susceptible  to 
oxidation  when  exposed  to  the  air  or  oxygen  gas,  thus 
forming  oxidized  products  of  a  resinous  nature  and  at  the 
same  time  always  giving  rise  in  the  presence  of  water 
(whenever  they  contain  any  terpenes)  to  the  formation  of 
hydrogen  dioxide  :  ozone  is  not  produced. 

The  following  is  a  list  of  some  of  the  better  known 
essential  oils,  showing  the  nature  of  their  chief  constituents  : 

American  turpentine  oil,  containing  dextro-pinene  (C10H16,  aterpene). 

French  ,,  ,,  ,,          laevo-pinene  (C10H]6,  a  terpene). 

Russian  ,,  ,,  ,,          sylvestrene  (C10H]6,  a  terpene). 

Camphor  oil  ,,  camphor  (C10H16O,  a  ketone  and 

a  terpene). 

Eucalyptus  oils  ,,  eucalyptol  (an  ether)  and  euca- 

lyptene  and  phillandrene  (ter- 
penes). 

Orange  oil  ,,  hesperidene  and  limonene  (ter- 

penes). 

Lemon  oil  ,,  limonene  (a  terpene)  and  citral 

(an  aldehyde). 

Thyme  oil  ,,  thymene  (a  terpene)  and  thymol 

(C10H14O,  a  phenol). 

Sandal  wood  oil  ,,          santene  (a  terpene). 

Citronella  oil  ,,          geraniol  (an  alcohol). 

Peppermint  oils  ,,          menthol  (an  alcohol). 

Spearmint  oil  ,,          carvone  (a  ketone). 

Wintergreen  oil  , ,          methyl  salicylate. 

Cinnamon  oil  ,,          cinnamic  aldehyde. 

In  the  umbeUifcrit,  the  essential  oil  is  most  abundant  in  the 
seeds  ;  in  the  aurantiacea,  both  fruits  and  flowers  yield  oil ; 
the  rosacea  contain  oil  only  in  the  petals  ;  while  the  myvtacecB 
and  the  labiata  yield  most  from  the  leaves.  As  further 
illustrating  the  immense  variety  of  character  of  essential 
oils,  it  may  be  mentioned  that  there  are  more  than  200 
species  of  the  eucalyptus,  and  all  the  oils  vary  in  character. 
The  better  known  ones  are  the  amygdalina,  globulus,  oleosa, 
odorata,  rcstata,  dumosa,  and  citviodova  oils.  These  oils 
are  all  produced  by  distillation  of  the  parts  of  the  trees  con- 
taining them,  whilst  turpentine  oil  is  produced  as  described 
elsewhere.  The  eucalyptus  globulus  oil  has  a  sp.  gr.  of 
from  0*910  to  0*930,  and  contains  as  its  principal  con- 
stituent from  50  to  80  per  cent,  of  a  substance  called 
eucalyptol,  also  known  as  cineol  (C10H18O) — a  clear,  colour- 
less liquid  which  can  be  frozen  to  a  crystalline  mass  at 
-  i°to  3°  C.  Phellandrene  is  a  terpene  (C10H]6)  forming  a 
large  proportion  of  the  amygdalina  oil. 


i82  ESSENTIAL  OILS— ESTERS 

ESSENTIAL  OILS  (Continued)— 

Many  of  the  essential  or  ethereal  oils  are  described  under 
their  individual  names.  (See  also  Balsams,  Eucalyptus, 
Terpenes,  and  Turpentine.) 

ESTER  GUMS— Substitutes  for  the  harder  natural  resins 
made  by  combining  the  acid  resins  with  alcohols,  such  as 
glycerine.  They  are  soluble  in  oil  and  turpentine, 
have  acid  values  as  low  as  from  2  to  20,  and  are  stated  to 
be  much  more  suitable  than  ordinary  resin  for  use  in 
making  varnishes  and  enamels.  To  prepare  them,  the 
softer  parts  of  the  resin  are  removed  by  distillation  in  a 
vacuum  or  a  current  of  superheated  steam,  and  the  residue 
is  heated  with  an  equivalent  proportion  of  glycerine,  phenol, 
or  naphthol,  to  a  high  temperature  with  a  dehydrating  agent. 

Resin  esters  can  be  formed  with  glycerine  by  heating 
together  at  from  280°  to  300°  C.,  and  passing  a  current  of 
hydrochloric  acid  gas,  carbon  dioxide,  or  air  through  the 
mixture. 

Ester  gums  are  used  in  making  enamel  paints,  and  more 
particularly  (in  conjunction  with  china- wood  oil)  for  water- 
proof varnishes  for  boats,  yachts,  etc. 

ESTERS — Many  alcohols  react  with  acids,  like  metallic  hydrox- 
ides and  form  what  are  termed  alkyl  salts  or  esters ;  for 
example,  ethyl  alcohol  and  acetic  acid  by  interaction  give 
ethyl  acetate  and  water — 

C2H6OH  +  CH3CO,OH  =  CH3,COO,C2H5  +  H2O, 

the  replaceable  hydrogen  atoms  of  the  carboxylic  group 
(CO, OH)  being  exchanged  for  alkyl  radicals,  and  the  pro- 
cess is  known  as  esterification. 

The  esters  so  produced  from  the  fatty  acids  are  more  or 
less  volatile  neutral  liquids  which  are  readily  hydrolyzed 
when  heated  with  water  or  alkalies  or  acids  back  again 
into  the  corresponding  alcohols  and  acids. 

Monobasic  acids  such  as  nitric  acid  yield  only  one  kind  of 
ester  termed  "  normal  or  neutral  esters,"  but  dibasic  acids 
yield  two  series  termed  "  acid  esters  "  and  "  neutral  esters  "  ; 
thus  ethyl  nitrate  is  (C2H5)NO3,  while  we  have  the  two 
ethyl  sulphates  (C2H5),HSO4  and  (C2H5)2SO4.' 

The  fats,  palmitin,  stearin,  and  olein  are  solid  esters,  or 
glyceryl  esters  of  respectively  palmitic,  stearic,  and  oleic 
acids,  and  are  resolved  by  hydrolysis  into  glycerol  (glycerine) 
and  the  several  fatty  acids  ;  thus  stearin — 


ESTERS-MTHER  183 

ESTERS  (Continued] — 

C3H5(C18H35O2)3  +  3KHO  (potassium  hydroxide)  = 
3K(C18H35O2)  (potassium  stearate)  +  C3H6(OH)3  (glycerine)- 
(See  Fats  and  Soaps.) 

Some  of  the  better  known  commercial  esters  are  alpha- 
betically listed  below : 

Amyl  acetate  Dimethyl  sulphate 

„      benzoate  Ethyl  acetate 
„     borate  „      aceto-acetate 

„      butyrate  „      benzoate 

„      formate  „      butyrate 

,,     valerianate  „      formate 

„      salicylate  „      salicylate 

Benzyl  acetate  Geranyl  acetate 

,,       benzoate  Glyceryl  tri-acetate 

,,       chloride  Methyl  salicylate 

Butyl  acetate  Tricresyl  phosphate 

,,      formate  Triphenyl        „ 

The  amyl  esters  of  formic,  acetic,  and  hexoic  (caproic)  acids 
are  among  the  odorous  constituents  of  apples.  (See  also 
Ethers.) 

ETCHING— See  Fluorine. 

ETHANE  or  ETHYL  HYDRIDE  (C2H6) — A  gaseous  hydro- 
carbon constituent  of  crude  petroleum.  (See  Hydrocarbons.) 

ETHER  or  .32THER  (Medium)  is  a  purely  "  hypothetical 
medium  of  great  elasticity  and  extreme  tenuity,  supposed 
to  pervade  all  space,  the  interior  of  solid  bodies  not  ex- 
cepted,  and  to  be  the  medium  of  transmission  of  light  and 
heat "  (Webster).  Humboldt  thought  of  the  universe  as 
filled  with  a  world-ether  or  volatile  fluid — densified  in  the 
nebulae,  more  so  in  the  comets  (yet  still  penetrable  by  the 
rays  of  light)  and  in  the  planets  as  of  all  degrees  of  density 
from  that  of  metals  to  that  of  honey,  water,  etc. 

Newton  calculated  upon  slender  data  that  imponderable 
ether  must  be  at  least  700,000  times  less  dense  than  air, 
basing  this  upon  the  velocity  of  the  propagation  of  sound! 
as  compared  with  that  of  light  deduced  from  the  horizontal 
parallax  of  the  sun. 

To  the  chemical  mind,  it  is  inconceivable  that  the 
interstitial  spaces  of  matter  can  be  occupied  by  this 
hypothetical  ether — as,  for  example,  an  atmosphere  of 
oxygen  gas.  So  far  as  such  a  conception  is  possible,  the 
result  would  be  a  mixture  of  oxygen  and  this  so-called 


1 84  ETHER— ETHERS 

ETHER  (Continued) — 

ether,  which,  however  imponderable,  must  have  qualities 
and  be  detectable  by  them. 

Oliver  Lodge  has  expressed  the  opinion  that  mechanical 
forces  cannot  be  exercised  across  really  empty  space  in  the 
completest  sense,  but  to  the  chemical  mind  there  are  no 
empty  spaces,  but  only  attenuated  atmospheres.  His 
reasoning  appears  to  be  paradoxical,  for  while  he  writes  of 
matter  and  ether  as  distinct  things,  yet  at  other  times  he 
describes  matter  as  essentially  composed  of  this  hypo- 
thetical ether. 

Chemically,  then,  the  conception  has  no  foundation,  for 
if  such  a  medium  existed  it  could  only  be  regarded  as  a 
universally  distributed  and  extremely  attenuated  form  of 
matter,  and  there  is  no  evidence  whatever  of  its  material 
existence.  (See  also  Porosity.) 

ETHEREAL — Nature  of  ether  ;  light,  volatile. 
ETHEREAL  SALTS — See  Ethers  (compound). 

ETHERS  (or  ALKYL-OXIDES)  are  a  class  of  compounds  which 
may  be  described  as  the  anhydrides  of  the  corresponding 
alcohols,  as  will  be  seen  by  comparison  of  the  formulae 
here  given : 


representing  2  molecules  of  ethyl  alcohol  from  which  a 
molecule  of  water  is  abstracted  by  the  action  of  sulphuric 
acid  at  140°  C.  The  ethers,  in  other  words,  correspond  in 
relation  to  the  alcohols  as  metallic  oxides  to  their  hydrates 
— C2H6HO  ethyl  alcohol,  (C2H^)2O  ethyl  ether,  NaHO 
sodium  hydrate,  Na2O  sodium  oxide. 

Ethyl  Ether  is  also  commonly  known  by  the  names  of 
"sulphuric  ether"  and  "vitriol  ether,"  and  is  a  mobile 
liquid  of  characteristic  odour,  soluble  in  alcohol,  and  very 
volatile  and  inflammable.  When  a  mixture  ;of  ether 
vapour  and  air  is  allowed  to  expand  suddenly  into  an 
evacuated  tube  it  is  found  to  ignite.  It  boils  at  34*9°  C., 
has  a  sp.  gr.  of  0*72,  and  is  an  excellent  solvent  of  oils,  fats, 
and  many  organic  substances  ;  and,  apart  from  its  extensive 
use  as  an  anaesthetic,  it  is  used  commercially  in  the  colour 
industry  and  in  the  preparation  of  collodion,  smokeless 
gunpowder,  etc. 

Methyl  Ether  (CH3)2O  is  a  gaseous  substance  at  ordinary 
temperatures,  but  liquefies  at  —  20°  C.,  and  is  prepared  on 


ETHERS  185 

ETHERS  (Continued)— 

a  considerable  scale  for  the  production  of  artificial  cold  by 
its  volatilization. 

ETHEES  (Compound),  or  ethereal  salts,  correspond  to  metallic 
salts,  and  are  formed  by  heating  alcohols  and  acids 
together  ;  thus,  for  example, 

C2H5HO  (ethyl  alcohol)  +  C2H4O2  (acetic  acid)  = 
C2H5,C2H3O2  (ethyl  acetate)  +  H2O  (water). 

They  are  for  the  most  part  volatile  liquids,  decomposed 
by  acids  and  alkalies,  but  some  of  them  are  solid  bodies, 
as,  for  example,  the  glycerides  found  in  fats.  (See  Esters.) 

Acetic  Ether  (ethyl  acetate)  (C2H5.C2H3O2)  is  a  colour- 
less, fragrant,  inflammable  liquid  of  sp.  gr.  0*9003,  and 
boiling-point  77*15°  C.,  soluble  in  water,  alcohol,  and 
ether.  It  is  prepared  by  heating  a  mixture  of  ethyl  alcohol, 
acetic  acid,  and  sulphuric  acid.  Dissolved  in  alcohol  it 
constitutes  the  so-called  "  essence  of  pears,"  and  is  ex- 
tensively used  as  a  solvent,  in  perfumery,  in  medicine,  and 
for  flavouring. 

Benzole  Ether  (ethyl  benzoate)  (C6H5CO2C2H5)  — A 
colourless,  aromatic  liquid  of  sp.  gr.  1*0509  and  boiling- 
point  212-9°  C.,  soluble  in  alcohol  and  ether;  prepared  by 
heating  ethyl  alcohol  and  benzoic  acid  in  presence  of 
sulphuric  acid ;  used  in  perfumery  and  for  flavouring 
(u  Essence  of  Niobe  "). 

Butyric  Ether  (ethyl  butyrate)  (C2H5(C4H7O2))  is  a 
colourless,  volatile  liquid  of  sp.  gr.  0*8788,  and  boiling- 
point  120*6°  C.,  soluble  in  alcohol  and  ether,  constituting 
the  so-called  "  essence  of  pine-apples,"  and  is  largely  used 
for  flavouring  extracts. 

Capric  Ether  (ethyl  caprate)  (C2H5(C10H19O2),  of  sp.  gr. 
0*87,  and  boiling-point  243°  C.,  is  used  in  making  wine 
bouquet  and  cognac  essence. 

Formic  Ether  (ethyl  formate)  (C2H5.HCO2)  is  a  mobile, 
colourless  liquid,  of  peach-like  odour;  of  sp.  gr.  0*9231, 
and  with  a  boiling-point  of  54*05°  C.  It  is  used  in  manu- 
facturing artificially  prepared  rum  and  arrack,  and  other- 
wise for  flavouring  purposes. 

Nitric  Ether  (C2H5NO3)  is  a  colourless,  inflammable 
liquid  of  pleasant  odour,  of  sp.  gr.  1-116  and  boiling-point 
87*6°  C.  It  is  soluble  in  alcohol,  and  is  prepared  by  heating 
a  mixture  of  alcohol,  urea  nitrate,  and  nitric  acid,  followed 
by  distillation. 


i86  ETHYL  ALCOHOL— EUCALYPTUS  OIL 

ETHYL  ALCOHOL — See  Alcohols. 
ETHYL  BENZOATE— See  Ethers  (Benzole). 

ETHYL  BROMIDE  (C2H5Br)— A  liquid  substitution  product 
of  ethane,  of  sp.  gr.  1-468,  soluble  in  alcohol  and  ether  ; 
used  as  a  local  anaesthetic,  and  for  the  relief  of  migraine, 
asthma,  and  convulsions. 

ETHYL  ETHER— See  Ethers. 

ETHYL  NITRATE— See  Ethers  (Nitric). 

ETHYL  VALERIATE  (C2H5(C5H9O2))  is  a  colourless  liquid 
of  pleasant  odour,  with  a  sp.  gr.  of  0-8765  and  boiling- 
point  144*5°  C->  use-d  m  compounding  perfumes,  etc. 

ETHYLAMINE — See  Amines. 

ETHYLENE— See  defines  and  Hydrocarbons. 

ETHYLENE  CHLORIDE  (CH2C1.CH2C1)— An  oily  liquid  anaes- 
thetic of  sp.  gr.  .1-2823,  soluble  in  water,  alcohol  and  ether. 

EUCAINE  (C15H21NO2) — A  white,  crystalline,  organic  com- 
pound used  as  a  substitute  for  cocaine. 

EUCALYPTOL  (Cineol)— See  Cineol  and  Essential  Oils. 

EUCALYPTUS  OIL — This  oil  varies  with  the  species  (varying 
from  very  large  trees  to  dwarf  bushes),  from  which  it  is 
produced,  and  there  are  upwards  of  200  species,  so  that 
the  oils  of  commerce  are  often  of  mixed  character  and 
constitution,  the  several  constituents  (phellandrene,  cineol, 
citral  or  geranial,  pinene,  and  terpenes)  varying  accord- 
ingly in  their  proportions.  They  are  all  soluble  in  alcohol, 
ether,  chloroform,  and  carbon  disulphide,  and  are  used  in 
medicine,  in  perfumery,  and  some  of  them  in  the  flotation 
process  of  ore  concentration.  The  sp.  gr.  varies,  for  the 
reasons  above  given,  from  0-850  to  0-940. 

The  globulus  variety  is  generally  preferred  to  the 
amygdalina  oil  on  account  of  its  superior  content  of 
eucalyptol  and  its  density  of  odour,  but  as  sanitary  agents 
there  is  little  to  choose  between  the  many  kinds  of  oil  that 
are  available.  The  globulus  oil  has  a  sp.  gr.  of  from 
0-91  to  0-93;  refractive  index,  1-469  to  1-475;  rotation 
+  10°  to  -  10°,  and  contains  from  50  to  80  per  cent,  of 
cineol  (C10H18O),  which  is  soluble  in  alcohol. 

The  Amygdalina  Oil  has  a  sp.  gr.  of  0-855  to  0-89,  and 
a  rotation  of  -  25°  to  -  8o°-  It  is  not  nearly  so  pungent 
in  odour  as  the  globulus  oil,  and  the  terpene  named 
phellandrene  is  its  chief  constituent 


EUCALYPTUS  OIL—EUGENOL  187 

EUCALYPTUS  OIL  (Continued)— 

The  Citriodora  Oil  has  a  sp.  gr.  of  0-87  to  0-905,  and  a 
rotation  of  -o°  to  +2°.  It  has  a  characteristic  odour, 
does  not  contain  cineol,  but  consists  chiefly  of  citronellol. 
(See  also  Essential  Oils.) 

EUCLASE — A   native   silicate   of   aluminium   and   glucinum, 
otherwise  known  as  prismatic  emerald. 

EUDIOMETER — A  simple  form  of  this  apparatus,  used  for  the 
examination  of  gases,  is  a  long  glass  tube,  closed  at  the 
one  end  and  open  at  the  other,  graduated  into  cubic  centi- 
metres by  divisions  etched  on  it.  At  the 
closed  end,  thin  wires  of  platinum  are 
fused  into  and  through  the  glass,  and 
thence  pass  outside,  so  that  they  can  be 
connected  with  the  wires  of  an  electric 
coil.  In  using  this  apparatus  to  demon- 
strate the  composition  of  water,  a  mixture 
of  2  volumes  of  hydrogen  and  i  volume 
of  oxygen  is  introduced  into  the  tube, 
which  is  then  inverted  and  placed  with 
its  open  end  in  a  trough  of  mercury. 
Upon  now  causing  an  electric  spark  to 
pass  from  end  to  end  of  the  two  wires 
within  the  tube,  the  two  gases  will  combine  with  explosive 
force.  In  this  way,  it  is  found  that  2  volumes  of  hydrogen 
and  i  volume  of  oxygen  combine  to  form  water,  and  if 
there  be  any  excess  of  either  gas  contained  in  the  mixture 
it  will  remain  after  the  condensation  that  takes  place  in 
the  eudiometer  following  upon  the  explosion.  (See  Volta- 
meter.) 

In  laboratories  where  a  mercury  bath  is  available,  this 
form  of  eudiometer  may  be  used  also  to  demonstrate  the 
proportion  of  oxygen  present  in  a  given  volume  of  air  by 
inverting  the  graduated  tube  containing  some  air  (the  rest 
of  the  tube  being  occupied  by  mercury)  over  the  bath,  and 
introducing,  by  means  of  a  pipette  with  a  recurved  end, 
some  few  cubic  centimetres  of  a  mixture  of  i  part  pyrogallic 
acid  in  6  parts  of  water  rendered  alkaline  by  the  addition 
of  caustic  potash  solution.  This  solution  rises  up  through 
the  mercury  in  the  tube,  absorbs  the  oxygen  of  the  air, 
becoming  dark  brown  in  colour  in  consequence,  and  leaves 
the  nitrogen  unabsorbed,  the  diminution  in  volume  thus 
becoming  apparent. 

EUGENOL— See  Cloves. 


i88  EUONYMIN— EXOTHERMIC  COMPOUNDS 

EUONYMIN— An  oleo-resinous  body  from  the  bark  of   the 

'spindle-tree  (Euonymus   europaus),  insoluble   in   water   but 

soluble  in  alcohol,  and   said  to  have  tonic  and   laxative 

properties;  it   is   used   medicinally  in  treatment   of  liver 

complaints. 

EUROPIUM  (Eu)— Atomic  weight,  152.  An  exceedingly 
rare  element  belonging  to  the  Terbium  group,  of  which 
little  is  known,  occurring  in  samarskite,  orthite,  cerite,  and 
gadolinite,  etc. 

"  EUSOL  " — A  proprietary  antiseptic  solution  containing  hypo- 
chlorous  acid ;  prepared  by  interaction  between  so-called 
chloride  of  lime  and  boric  acid. 

EUTECTIC — A  term  given  to  a  solidified  mixture  of  solute 
and  solvent  of  the  lowest  melting-point ;  for  example,  a 
molten  mixture  of  zinc  (which  melts  at  419°  C.)  and  cad- 
mium (which  melts  at  321°  C.)  yields  by  solidification  of 
one  or  other  metal  during  cooling  a  eutectic  mixture  which 
contains  73  per  cent,  cadmium  and  solidifies  at  270°  C. 

EVAPORATION — The  passage  from  the  liquid  to  the  vaporous 
state,  as  when  water  is  evaporated  by  the  agency  of  heat 
into  steam.  Many  liquids  may  be  concentrated  by  means 
of  evaporation,  and  for  this  purpose,  chemists  employ 
vessels  termed  evaporating  basins  or  dishes.  In  this  way 
the  excess  of  water  or  other  solvent  which  holds  the 
chemical  substance  in  solution  is  dissipated  by  evaporation. 
The  process  is  also  often  conducted  in  a  retort,  so  that  the 
solvent,  if  valuable,  can  be  condensed  and  recovered. 

Evaporation  is  retarded  to  some  extent  by  salts  and 
other  soluble  substances  in  solution,  as  compared  with  that 
of  water. 

Evaporating  basins  are  also  often  employed  to  obtain 
substances  in  a  crystallized  condition,  or  for  drying  solid 
masses  or  pasty  mixtures  by  heating.  They  are  made  of 
various  sizes,  from  2  inches  in  diameter  up  to  12  inches  or 
more,  the  larger  ones  being  of  porcelain,  glass,  and  silica. 
Some  smaller  ones  are  made  of  silver,  aluminium,  platinum, 
and  nickel  (the  choice  being  made  according  to  the  nature 
of  the  chemicals  to  be  dealt  with),  and  all  are  preferably 
provided  with  a  lip  to  facilitate  the  transfer  of  their  liquid 
contents  to  other  vessels  as  and  when  required. 

EXHALATION — The  act  of  exhaling  (breathing  out)  or  passing 
out  of  vapours. 

EXOTHERMIC  COMPOUNDS— See  Heat. 


EXPANSION— EXPLOSIVES  189 

EXPANSION — The  act  of  occupying  a  greater  space.  Gases, 
in  particular,  are  easily  expanded  by  heat. 

EXPLOSIVES — Explosives  are  substances  which,  under  the 
influence  of  heat  or  shock,  or  both,  are  instantly  resolved 
into  gases  occupying  at  the  high  temperature  of  explosion 
comparatively  enormous  volumes,  and  consequently  exert- 
ing tremendous  pressure  which  disrupts  the  objective  or 
drives  projectiles  out  of  guns. 

They  may  be  said  to  consist  of  bodies  such  as  nitro- 
glycerine and  nitro-cellulose,  which  are  explosive  in  them- 
selves, or  mixtures  of  substances  which,  separately,  are  or 
may  be  non-explosive,  but  when  intimately  mixed  are 
capable  of  being  exploded  either  by  ignition  or  detonators. 

Gunpowder  is  a  mechanical  mixture  of  nitre,  or  Chili 
nitre,  charcoal,  and  sulphur  in  proportions  of  about  75,  15, 
and  10  respectively,  and  is  still  largely  employed  for 
blasting  purposes,  although  it  has  ceased  to  be  used  as  a 
military  propellant,  or  nearly  so.  Its  explosive  power  is 
due  to  an  enormous  evolution  of  gas  from  a  relatively  small 
quantity  of  solid  substance.  The  nitre  supplies  the  oxygen 
necessary  for  burning  up  the  carbon  and  the  sulphur,  at 
the  same  time  yielding  nitrogen  gas,  It  is  a  so-called 
"  low  explosive,"  while  the  "  high  explosives "  have  a 
velocity  of  explosion  some  500  times  greater.  These  high 
explosives  are  rich  in  nitrogen,  and  when  detonated,  furnish 
large  quantities  of  that  gas  and  others  which  are  enor- 
mously expanded  by  the  heat  generated  by  the  chemical 
changes  which  take  place,  so  that  they  amount  to  from 
10,000  to  15,000  times  the  volume  of  the  explosive  sub- 
stance itself. 

Just  as  nitre  supplies  the  oxygen  necessary  to  burn  the 
charcoal  and  sulphur  contained  in  gunpowder,  so  (by 
chemical  means)  hydrogen  is  removed  from  cotton  (cellu- 
lose), glycerine,  phenol,  toluene,  etc.,  and  is  substituted  by 
groups  of  the  radical  NO2,  which  contain  and  supply 
the  oxygen  essential  to  the  combustion  of  the  associated 
carbon  and  hydrogen,  the  carbon  being  converted  into 
gaseous  oxides  and  the  hydrogen  into  steam,  while  at  the 
same  time,  the  nitrogen  is  also  set  free  in  the  form  of  gas. 
Some  of  these  substances,  and  their  nitrated  forms,  may  be 
roughly  indicated  as  follows  : 

Cellulose  (C6H10O5)  is  chemically  changed  into  nitro- 
cellulose or  gun-cotton  (C12H14O10(NO2)6). 

2C6H1005  +  6HN03  =  C12H14010(N02)6  +  6H2O. 


190  EXPLOSIVES 

EXPLOSIVES  (Continued)— 

Glycerine  (C3H8O3)  becomes  changed  to  nitro-glycerine 
(C3H6(O.N02)3). 

Phenol  (CfiH6O)  becomes  changed  to  tri-nitro-phenol 
(C6H2(N02)3OH). 

Toluol,  or  toluene  (C7H8),  becomes  changed  to  tri- 
nitro-toluol  (C7H5(NO2)3). 

Nitrc-G-lycerine  is  a  pale  yellow,  odourless,  heavy 
body  of  oily  consistency,  and  sp.  gr.  r6,  obtained  by  the 
action  of  strong  nitric  acid  upon  glycerine.  It  is  soluble 
in  alcohol  and  ether.  When  decomposed  by  explosion  the 
chemical  changes  that  occur  are  represented  by  the  follow- 
ing equation,  from  which  it  will  be  seen  that  the  whole  of 
the  oxygen  that  is  required  is  self-supplied,  and  that  all 
the  products  are  gaseous  at  the  temperature  of  the 
explosion. 

2(C3H5N3O9)  =  6CO2  +  5H2O  +  3N2  +  O. 

Dynamite,  so  largely  used  for  blasting  purposes  in  mines 
and  otherwise,  is  a  mixture  of  nitro-glycerine  and  the 
infusorial  earth  named  kieselgiihr,'  and  has  given  a  velocity 
wave  of  6,000  metres  per  second. 

Blasting  gelatine — a  stiff  jelly — is  the  strongest  of  all 
nitro-glycerine  explosives,  and  other  varieties  consist  of  a 
thin  jelly  of  nitro-glycerine  thickened  with  from  3  to  6  per 
cent,  collodion  cotton  worked  up  into  a  plastic  mass  with 
suitable  proportions  of  potassium  nitrate  and  wood-meal. 

Nitro-glycerine  explosives  freeze  at  8°  C.,  and  have  to 
be  thawed  before  use. 

Picric  Acid,  or  tri-nitro-phenol  (C6H2(NO2)3OH),  is 
obtained  by  the  graduated  action  of  strong  nitric  acid  upon 

?henol  (carbolic  acid),  and  is  itself  a  high  explosive, 
t  has  given  a  velocity  of  7,700  metres  per  second.  Various 
mixtures  of  it  with  collodion — a  nitrated  cellulose  prepared 
from  gun-cotton  by  dissolving  it  in  mixtures  of  ether, 
alcohol,  and  other  bodies — in  compressed  and  molten  forms 
constitute  the  explosives  melinite  and  lyddite. 

Gun-Cotton,  or  tri-nitro-cellulose,  is  obtained  by  the 
graduated  action  of  nitric  and  sulphuric  acids  upon  cellu- 
lose (cotton- waste),  and  smokeless  gunpowders  and  most 
of  the  violent  propellants  contain  gun-cotton. 

Dry  gun-cotton  is  one  of  the  most  dangerous  explosives, 
as  when  dry  and  warm  it  is  very  liable  to  explosion  by 
friction. 


EXPLOSIVES 


191 


EXPLOSIVES  (Continued)— 

Tri-nitro-cellulose  is  a  yellowish,  amorphous  substance 
soluble  in  alcohol,  ether,  benzol,  acetone,  amylacetate,  etc. 
Cordite  is  an  important  military  propellant,  and  is  a 
mixture  of  gun-cotton  and  nitro-glycerine  dissolved  in 
acetone  and  thickened  and  rendered  more  stable  with  about 
5  per  cent,  of  vaseline.  The  excess  of  acetone  is  afterwards 
evaporated  off  from  the  gelatinous  mass,  which  is  prepared 
in  cord  form. 

Gelignite  is  a  mixture  of  nitro-glycerine,  nitro-cellulose, 
wood-pulp,  and  potassium  nitrate  (KNO3). 

Tri-Nitro-Toluol  (T.N.T.)  is  obtained  by  the  graduated 
action  of  strong  nitric  acid  upon  toluol  (toluene)  (a  deriva- 
tive of  benzene  obtained  from  coal  tar),  in  the  form  of 
yellow  prismatic  crystals  melting  at  80-5°  C.,  and  has  re- 
placed picric  acid  to  a  large  extent  as  a  filling  for  shells, 
being  more  stable  in  character  and  cheaper. 

Amatol — An  explosive  made  by  admixing  20  parts 
T.N.T.  with  80  parts  ammonium  nitrate,  which  gradually 
superseded  other  high  explosives,  including  picric  acid, 
during  the  recent  war,  as,  although  less  rapid  and  shatter- 
ing than  T.N.T.,  it  gives  greater  flame,  is  cheaper,  and 
practically  smokeless,  due  to  the  excess  of  oxygen  provided 
by  the  ammonium  nitrate. 

Ammonal — An  explosive  of  the  ammonium  nitrate  class, 
resembling  amatol,  containing  finely  divided  aluminium  in 
admixture. 

Cheddite  is  an  explosive,  the  chief  ingredient  of  which  is 
potassium  chlorate  (about  79  per  cent),  made  up  of  nitro- 
naphthalene  or  di-nitro-toluene  (about  15  per  cent.)  and 
from  5  to  6  per  cent,  castor  oil. 

Blastine  is  another  explosive  of  the  chlorate  type. 

Roburite  is  the  name  of  a  smokeless  and  flameless  mining 
explosive,  in  the  compounding  of  which  chloro-di-nitro- 
benzene  is  employed  (as  also  in  "  Bellite  "),  in  admixture 
with  ammonium  nitrate. 

Umbrite  is  an  explosive  containing  49  parts  of  nitro- 
guanidine,  38  parts  ammonium  nitrate,  and  13  of  silicon; 
stated  to  be  but  slightly  hygroscopic  and  well  retaining  its 
explosive  power  even  when  moist. 

The  amount  of  blasting  explosives  (excluding  cordite, 
smokeless  powder,  sporting  ammunition,  etc.)  manufactured 
in  this  country  before  the  war  was  about  17,500  tons  per 
annum. 


192  EXPLOSIVES—  FATS 

EXPLOSIVES  (Continued)— 

Liquid  oxygen  explosives  are  made  by  saturating  an 
absorptive  combustible  such  as  soot,  lamp-black,  or  cork- 
meal,  with  liquefied  oxygen,  and  are  stated  to  be  stronger 
than  black  powder,  and  can  be  used  for  some  purposes 
instead  of  dynamite. 

EXTRACTION  —  Taking  or  drawing  out  —  a  solvent  action  by 
means  of  which  the  parts  of  a  substance  soluble  in  the 
solvent  are  extracted  —  that  is,  separated  from  the  other 
parts. 

EXTRACTS  —  A  pharmaceutical  term  descriptive  of  the  con- 
centrated preparations  obtained  by  evaporation  of  infusions 
or  extracts  prepared  by  the  action  of  solvents. 

FARINA  —  Potato  or  corn  starch. 

FARINACEOUS—  Starchy. 

FAT  HARDENING—  See  Hydrogen,  p.  252. 

FATS  —  Most  animal  and  vegetable  fats,  including  suet,  tallow, 
butter,  and  many  of  the  various  fish  and  nut  oils,  are 
mixtures  of  .distinct  fats  or  substances  chemically  termed 
glycerides  or  "  glyceryl  esters"  of  stearic,  palmitic,  and  oleic 
acids.  The  two  former  acids  are  solid  and  the  last-named 
fluid  in  their  separate  forms,  and  the  consistence  of  a  fat  or 
oil  depends  upon  the  relative  proportion  of  these  several  fat 
constituents,  named  individually,  stearin,  palmitin,  and 
olein.  Lard  does  not  contain  tri-stearin.  In  other  words, 
these  fats  or  esters  are  combinations  of  fatty  acids  and 
glycerine.  They  all  melt  well  below  100°  C.,  and  are  all 
saponifiable,  yielding  soaps  and  glycerine  by  the  process. 

The  constitution  of  fat  is  illustrated  by  showing  the 
constitutional  formulae  of  glycerine  and  (for  example) 
stearin,  side  by  side  — 

[HO 
C3H6   HO  C3H6 


HO  c18H35o2 

Glycerine.  Stearin  or  tri-stearin. 

When  stearin  is  saponified  with  caustic  soda,  the  follow- 
ing change  takes  place  : 

C3H6(C18H3602)3  +  3NaHO  =  3Na(C18H35O2)  +  C3USO^ 

—  that   is   to   say,   sodium    stearate   (or   soda   soap)    and 
glycerine  (or  glycerol)  are  produced. 

Fats  and  fatty  acids  are  largely  used  in  the  manufacture 
of  soaps,  candles,  and  margarine  ;  tallow  and  bone-fat  and 


FATS— FEELING'S  SOLUTION  193 

FATS  (Continued)— 

some  oils  are  used  in  connection  with  the  sizing  of  certain 
textiles  to  soften  the  effect  of  starch ;  whilst  nut  and  fish 
oils  have  in  recent  years  acquired  growing  importance 
on  account  of  the  ever-increasing  demand  for  margarine. 
"Stearine  candles"  consist  for  the  most  part  of  stearic 
acid,  some  proportion  of  paraffin  or  wax  being  added  to 
prevent  crystallization,  the  stearic  acid  being  obtained  by 
hydrolysis  of  the  beef  and  mutton  fats  by  treatment  with 
superheated  steam,  or  dilute  sulphuric  acid,  or  lime  and 
water.  When  steam  is  used,  the  glycerine  distils  over 
with  the  steam,  the  fatty  acids  being  left  behind. 

The  Twitchell  process  of  saponifying  fats  so  as  to  obtain 
glycerine  and  fatty  acids  directly,  without  the  use  of  alkalies 
or  by  heating  under  pressure,  employs  a  reagent  obtained 
by  allowing  an  excess  of  sulphuric  acid  to  act  on  a  solution 
of  oleic  acid  dissolved  in  an  aromatic  hydrocarbon,  such  as 
benzene  or  naphthalene. 

The  cleansed  fat  or  oil  is  mixed  with  50  per  cent,  of 
distilled  water  containing  about  2  per  cent,  of  the  reagent, 
and  the  mixture  is  heated  and  kept  stirred  by  means  of  an 
open  steam  coil  for  from  ten  to  fifty  hours,  according  to  the 
nature  of  the  fat  and  until  it  is  saponified.  At  the  con- 
clusion of  the  process,  the  underneath  layer  contains  all  the 
glycerine  in  watery  solution,  and  the  upper  layer  contains 
the  free  fatty  acids. 

The  "  acid  value  "  of  fats  is  the  number  of  milligrammes 
of  potassium  hydroxide  required  to  neutralize  the  free  fatty 
acids  contained  in  i  gramme. 

The  rancidity  of  fats  is  regarded  by  some  writers  as 
resulting  from  bacterial  action  on  the  glycerides,  but  by 
others  as  due  in  the  first  place,  to  the  formation  of  super- 
oxides  of  the  unsaturated  glycerides,  and  their  subsequent 
decomposition  (attended  with  the  production  of  aldehydes 
and  aldo-acids)  by  the  joint  action  of  moisture  and  micro- 
organisms. (See  also  Tallow,  Waxes,  Oils,  Glycerine, 
Soaps,  and  Hydrogenation.) 

FATTY  ACIDS— See  Acids  and  Fats. 

FATTY  ACIDS  FROM  HYDROCARBONS— See  Petroleum. 

FEHLING'S  SOLUTION — A  solution  of  cupric  sulphate  mixed 
with  Rochelle  salt  (a  double  tartrate  of  potassium  and 
sodium)  and  alkali,  used  as  an  oxidizing  agent  and  em- 
ployed as  a  test  for  the  determination  of  inverted  sugars 
or  other  reducing  agents  in  solution,  by  ascertaining  the 


194          FEELING'S  SOLUTION—  FERMENTATIONS 

FEELING'S  SOLUTION  (Continued)— 

amount  of  cuprous  oxide  produced  by  its  action.  Sugar 
itself  does  not  reduce  Fehling's  solution,  and  requires  to  be 
first  of  all  inverted. 

FELSPARS  —  Compound  mineral  silicates  of  aluminium  and 
other  metals  found  abundantly  in  nature.  There  are  many 
deposits  in  Cornwall,  Ireland,  Wales,  and  Scotland,  as 
much  as  14  per  cent,  potassium  oxide  (K2O)  being  found  in 
some  small  veins  of  orthoclase,  or  potash-  felspar,  although 
most  of  them  are  not  suitable  for  potash  extraction.  (See 
Potassium.) 

FELT  consists  of  wool  or  hair  worked  into  sheet  form  by 
being  matted  together. 

FENNEL  OIL  —  A  colourless,  aromatic  oil  from  common  fennel 
(A  net  hum  faniculum\  to  some  extent  identical  with  oil  of 
aniseed.  It  is  soluble  in  alcohol,  ether,  etc.,  and  used  in 
perfumery  and  in  making  liqueurs. 

The  sp.  gr.  varies  from  0-884  to  0*974  and  the  refractive 
index  from  i'4756  to  1*5335  according  to  the  kind  and 
mode  of  preparation. 

FERMENTATIONS—  Chemical  changes  brought  about  by  yeast 
and  other  forms  of  cell  life,  including  bacteria,  in  suitable 
media,  but  directly  due  to  enzymes,  which  are  produced  by 
or  contained  in  the  living  cells.  The  act  of  fermentation 
is  generally  accompanied  with  liberation  of  gas  (effer- 
vescence) and  the  evolution  of  heat. 

Yeast  cells,  for  example  (saccharomyces),  or  an  extract 
prepared  from  them,  but  free  from  the  living  cells,  contain 
zymase,  an  enzyme  which  breaks  up  sugar  to  the  extent  of 
about  95  per  cent,  into  alcohol  and  carbon  dioxide  — 


A  medicinal  preparation  known  as  zymine  is  now  made 
by  the  extraction  of  moist  yeast  cells  with  acetone,  and, 
while  it  is  quite  incapable  of  growth  or  reproduction,  it  is 
much  more  active  in  inducing  fermentation  than  they  are. 
The  most  favourable  temperature  for  fermentation  is  from 
25°  to  30°  C.,  and  living  yeast  cells  are  killed  when  the 
alcoholic  strength  of  the  product  reaches  about  14  per  cent. 

The  lactic  fermentation  or  souring  of  milk,  is  induced  by 
a  bacterium  known  as  the  Bacterium  lactis,  but  if  a  mixed 
fermentative  agent  is  employed,  such  as  old  cheese,  which 


FERMENT  A  TIONS— FERTILIZERS  195 

FERMENTATIONS  (Continued)— 

contains  many  kinds  of  ferment,  the  lactic  acid  first  of  all 
produced  is  changed  into  butyric  acid. 

In  the  butyric  fermentation  of  starch  or  sugar,  induced 
by  the  Bacillus  butyricus,  butyric  acid  (C4H8O2)  is  produced. 
The  change  of  alcohol  into  acetic  acid,  as  experienced  in 
the  souring  of  light  wines  or  beer,  is  another  act  of  fermen- 
tation due  to  enzymes.  (See  also  Beer,  Enzymes,  Wine, 
and  Yeast.) 

FERRATES  — Compounds  corresponding  to  the  manganates,  of 
which  potassium  ferrate  (K2FeO4)  is  illustrative. 

FERRIC  SALTS— See  Iron. 

FERRICYANIDES  are  compound  cyanides  produced  from 
ferrocyanides  by  the  action  of  oxidizing  agents — for 
example,  potassium  ferrocyanide  (2K4FeCN6)  becomes 
converted  into  K6(FeCN6)2  or  2K3Fe(CN)6  (potassium 
ferricyanide).  (See  Potassium  Compounds.) 

FERRITES — Compounds  of  ferric  oxide  with  other  oxides — 
for  example,  zinc  ferrite  (Fe2O3,ZnO). 

FERRO-ALLOYS— See  Iron. 
FERROCERIUM— See  Pyrophoric  Alloys. 

FERROCYANIDES — Compound  cyanides  of  iron  and  other 
metals,  of  which  potassium  ferrocyanide  is  typical.  They 
are  produced  from  ferricyanides  by  the  action  of  reducing 
agents,  potassium  ferricyanide,  for  example,  yielding  the 
ferrocyanide  by  the  action  of  grape  sugar  in  presence  of 
potassium  hydrate.  (See  Potassium  Compounds  and 
Prussian  Blue.) 

FERROUS  SALTS— See  Iron. 

FERRUGINOUS— Containing  iron.  Many  natural  mineral 
waters  are  more  or  less  ferruginous  in  character  and  act  as 
tonics.  (See  Chalybeate  Waters.) 

FERTILIZERS  are  materials  applied  to  the  soil  to  assist  or 
promote  the  growth  of  vegetable  life,  and  as  the  well-being 
of  plants  depends  upon  an  adequate  supply  of  the  various 
constituents  found  in  them  and  necessary  to  their  existence 
and  full  development,  they  cover  a  very  wide  field  and  vary 
accordingly  with  regard  both  to  the  nature  of  the  soil  and 
the  characters  of  the  plants.  They  include  ordinary  stable 
manure  or  dung,  slaughterhouse  refuse,  blood,  bones,  am- 
monium sulphate,  nitrate,  and  chloride,  coprolites,  super- 
phosphate, basic  slag,  guano,  fish  meal,  fish  offal,  potash 


196  FERTILIZERS— FILTER  PRESSES 

FERTILIZERS  (Continued)— 

salts,  Chili  nitre,  oil  seed  cakes,  burnt  lime,  marl,  clay, 
soot,  seaweed,  gypsum,  etc.  Many  of  these  materials  are 
described  under  their  several  names. 

Ammonium  sulphate  as  produced  by  gasworks  contains 
about  24^  per  cent,  of  ammonia,  and  in  1914  the  total 
production  of  the  United  Kingdom  was  426,000  tons. 
There  is  little  to  choose  between  the  values  of  this  sub- 
stance and  nitre,  but  it*  is  said  that  ammonium  nitrate 
is  more  effective  than  ammonium  sulphate  for  the  growth 
of  mangolds  and  wheat. 

The  exigencies  of  war  compelled  Germany  to  erect 
plants  for  the  fixation  of  nitrogen  from  the  air,  and  it  has 
been  reported  that  the  whole  of  the  nitrogen  compounds 
required  for  making  explosives  and  for  agricultural  use  was 
produced  in  this  way.  In  this  direction  our  country  has 
now  followed  suit.  (See  Cyanamide,  Nitrogen,  Nitrogen 
Fixation,  and  Vegetation.) 

FIBRIN  (Syntonin) — A  constituent  of  the  blood  which  separates 
from  it  upon  coagulation  or  clotting.  It  is  of  an  albuminoid 
character,  and  its  composition  is  approximately  as  shown : 

Carbon         527 

Hydrogen 6-9 

Nitrogen      15-4 

Oxygen        23-5 

Sulphur        1-2 

Phosphorus 0-3 


lOO'O 


It  has  been  conjectured  that  the  clotting  of  blood  is 
brought  about  by  an  enzyme  in  the  blood  called  thrombin, 
but  this  has  not  been  definitely  determined. 

FILES  are  used  in  chemical  laboratories  for  a  number  of 
purposes,  and  are  of  three  sorts.  Triangular  ones  are  used 
both  for  marking  glass  and  assisting  in  the  breaking  of 
glass  tubing  by  partially  filing  through  the  surface  and  then 
applying  pressure  to  the  weakened  part.  The  round  ones 
are  chiefly  employed  for  filing  smooth  the  holes  made  in 
corks  by  borers,  or  for  enlarging  them  ;  whilst  flat  files  are 
used  for  smoothing  or  reducing  the  diameter  of  corks  and 
taking  the  ragged  edges  (by  gentle  rasping)  off  the  ends  of 
glass  tubes,  etc. 

FILTER  PRESSES  —  Mechanical  contrivances  of  various 
patterns,  consisting  essentially  of  a  frame  carrying  a 


FILTER  PRESSES-FILTERS  197 

FILTER  PRESSES  (Continued)— 

number  of  loose  slabs  of  filter  surface  which  can  be 
clamped  to  form  a  series  of  hollow  chambers  capable  of 
withstanding  internal  pressure,  the  filter  surface  being 
ribbed  or  grooved  and  covered  with  cloth.  Regard  must  of 
course  be  had  to  the  kind  of  cloth  and  the  necessary 
adaptation  according  to  the  chemical  and  physical  qualities 
of  the  subject  material. 

FILTERS  or  strainers  provide  the  means  of  separating  liquids 
from  solids.  The  common  laboratory  form  consists  of  a 
circular  piece  of  porous  paper  made  of  a  special  quality 
which  yields  a  minimum  amount  of  ash  when  burned  (in- 
cinerated). By  folding  it  first  of  all  into  halves  and  then 
again  into  quarters,  it  will  be  found,  when  opened  out,  to 
fit  into  a  funnel  of  appropriate  size,  the  paper  lying  against 
the  sides  of  the  funnel.  In  common  practice,  the  paper 
filter  when  so  fitted  and  before  use,  is  first  of  all  moistened 
with  a  liquid  of  the  same  nature  as  that  contained  in  the 
mixture  to  be  filtered.  Thus,  for  aqueous  mixtures,  water 
is  applied  from  a  wash-bottle  (which  see) ;  for  alcoholic 
mixtures,  alcohol  of  the  same  strength  should  be  used  ;  and 
so  forth. 

Whatman's  Extraction  Thimbles  are  made  of  specially 
prepared  filter-paper,  are  seamless,  and  can  be  used 
repeatedly  for  the  extraction  of  soaps,  fats,  foods, 
rubber,  etc. 

Paper  filters  can,  in  some  cases,  be  used  for  separating 
two  liquids  of  different  gravities  that  are  not  miscible — 
that  is,  cannot  be  mixed  together  so  that  they  will  not 
separate  again  after  shaking  and  upon  standing ;  for 
example,  a  mixture  of  turpentine  and  water  or  olive  oil 
and  water.  In  such  cases,  if  the  filter  be  first  of  all 
wetted  with  water  and  then  used,  the  watery  (aqueous) 
part  will  pass  through  the  filter -paper,  while  the  oily 
bodies  will  be  retained  more  or  less  permanently  on  the 
filter. 

There  are  filters  or  strainers  of  solid  porous  porcelain  or 
earthenware  which  are  sometimes  employed  for  straining 
liquids  from  magmas  or  thick,  moist  mixtures  of  crystalline 
or  other  solid  substances.  These  filters  sometimes  take  the 
fqrm  of  solid  flat  plates  on  which  the  magma  is  placed 
(taking  care  that  it  does  not  overflow  the  edges  of  the 
strainer),  and  the  liquid  part  gradually  soaks  or  flows  away 
through  the  texture  of  the  filter  block,  leaving  the  more  or 
less  dry  crystalline  or  other  solid  body  on  its  surface.  In 


198  FILTERS  -FIRE-DA  MP 

FILTERS  (Continued)— 

other  cases,  strainers  are  constructed  of  funnels  having 
their  necks  plugged  more  or  less  tightly  with  various 
materials  known  not  to  be  chemically  affected  by  the 
materials  to  be  filtered — as,  for  example,  glass-wool,  slag- 
wool,  asbestos  fibres,  cotton-wool,  flannel,  etc. 

Biichner  Funnel  is  a  type  of  filter  designed  for  the  filtration 
of  bulky  precipitates,  usually  made  of  stout  porcelain,  and 
consists  of  a  cylindrical  cup  of  diameter  5  to  15  cms.  wide 
and  3  to  5  cms.  deep.  The  flat  bottom  is  pierced  with  a 
number  of  holes  and  below  it  the  funnel  narrows  rapidly  to 
an  outlet  tube  i  to  2  cms.  in  diameter.  A  circular  sheet  of 
filter-paper  or  other  filtering  medium  is  laid  down  on  the 
perforated  bottom  so  as  to  cover  it  completely,  and  the 
cup  is  filled  up  with  the  liquid  to  be  filtered.  It  is  always 
used  in  conjunction  with  a  suction  filter  pump. 

In  manufacturing  and  industrial  operations,  appliances 
constructed  on  these  principles  are  extensively  employed, 
particularly  where  large  volumes  have  to  be  dealt  with, 
and  when  it  is  difficult  to  otherwise  separate  liquids  from 
the  mixtures  to  be  dealt  with.  In  laboratory  practice,  some 
such  preliminary  filtration  has  often  to  be  made  before  the 
clouded  filtrate  thus  prepared  can  be  more  perfectly  filtered 
— say  through  an  ordinary  paper  -  filter  as  previously 
described. 

Sand  is  used  in  waterworks  for  the  filtration  of  water  on 
a  large  scale,  and  there  are  many  types  of  domestic  filters, 
variously  prepared  for  the  purification  of  water.  In  some, 
animal  charcoal  pressed  into  blocks,  is  used  and  no  doubt 
it  assists  the  oxidation  of  organic  matters,  but  does  not 
sterilize  the  water. 

In  the  Chamberland-Pasteur  filter  a  cylinder  of  unglazed 
porcelain  is  used,  and  in  the  Berkfeld  filter  a  block  of 
baked  siliceous  earth  (kieselgiihr)  is  employed.  Both  of 
these  remove  the  micro-organisms  from  the  water,  but  they 
require  periodical  sterilization.  In  the  Bischof  filter,  iron 
prepared  in  a  spongy  form  is  used  as  the  purifying  agent 
and  is  very  useful  in  many  circumstances.  (See  Filter 
Presses.) 

FIRECLAY— See  Clays. 

FIRE-DAMP — An  explosive  gas  naturally  produced  in  coal- 
mines, and  chiefly  composed  of  methane  (marsh  gas,  CH4) 
admixed  with  air,  nitrogen,  and  some  carbon  dioxide. 


FIREPROOFING-FISH  OILS  199 

FIREPROOFING  (of  Wood) —A  paint  known  as  "  Calcimine" 
has  been  found  satisfactory  for  inside  purposes,  whilst  for 
outside  applications,  a  coating  of  zinc  borate  and  chrome 
green  ground  in  linseed  oil  exhibits  good  fire-resisting 
properties. 

FIREWORKS  (Pyrotechny)  are  luminous  devices  made  from 
combustible  or  explosive  chemicals,  largely  dependent 
upon  the  use  of  gunpowder,  metallic  filings  being  intro- 
duced to  produce  scintillation,  and  many  chemicals  being 
used  in  association,  to  produce  colouring  and  other  effects. 

FISH  GLUE— See  Glue. 

FISH  OILS  are  of  the  non-drying  class,  and  usually  have  an 
offensive  odour,  which,  however,  is  removed  in  the  chemical 
changes  brought  about  by  their  hydrogenation.  (See 
Hydrogenation  of  Oils.)  When  exposed  to  cold  they  are 
liable  to  deposit  solid  fat. 

Cod-Liver  Oil  is  obtained  from  the  liver  of  various  species 
of  Gadus,  and  especially  from  the  torsk  (Brosimus  brosme). 
It  has  a  sp.  gr.  of  from  0*92  to  0-93,  saponification  value 
171  to  189,  iodine  value  150  to  167,  and  refractive  index  1*479 
to  1*483.  It  is  largely  used  as  a  nutritive  food  and  in 
medicine. 

Dugong  Oil  (Manatee  Oil) — Obtained  from  the  blubber  of 
the  sea  cow  (Halicore  indicus] ;  sp.  gr.  0-92,  saponification 
value  197*5,  iodine  value  66-6.  It  is  used  to  replace  cod 
and  whale  oils  and  for  burning  (in  India). 

Herring  Oil  is  yellowish-red,  with  a  sp.  gr.  about  0*92, 
saponification  value  180  to  194,  iodine  value  130  to  142,  and 
is  soluble  in  carbon  disulphide,  benzene,  and  ether.   It  is  pre- 
pared by  boiling  and  pressing  herrings,  and  is  used  in  soap 
making  and  leather-dressing. 

Menhaden  Oil — A  yellowish-red  oil  extracted  from  the 
menhaden  or  moss-bunker  fish,  of  sp.  gr.  0-927  to  0*933, 
saponification  value  about  190,  and  iodine  value  140  to  180. 
It  is  soluble  in  ether,  naphtha,  carbon  disulphide,  and 
benzol,  and  is  used  in  leather-dressing,  etc. 

Porpoise  Oil  is  extracted  by  boiling  the  various  parts  of 
the  brown  porpoise,  and  is  of  pale  yellow  colour,  of  sp.  gr. 
about  0-926,  and  iodine  value  according  to  the  part  of  the 
body  yielding  same.  It  is  used  in  making  lubricants, 
soaps,  leather-dressing,  etc.,  and  is  soluble  in  ether,  chloro- 
form, carbon  disulphide,  and  benzol. 

The  quality  prepared  from  the  jaw  of  the  porpoise  is 
used  in  particular  as  a  lubricant  for  watches, 


200  FISH-OILS—FLAME  COLOURATION 

FISH  OILS  (Continued) — 

Sardine  Oil  is  prepared  like  herring  oil  and  is  of  a  yellow 
colour,  of  sp.  gr.  about  0-93,  saponification  value  about  190, 
iodine  value  180  to  193,  and  refractive  index  i'48.  It  is 
soluble  in  alcohol,  benzine,  etc.,  and  is  used  in  soap-making 
and  as  a  lubricant. 

Seal  Oil  derived  from  Squalus  maximus,  is  white  or  straw- 
coloured,  of  sp.  gr.  0-924  to  0-926,  with  saponification 
value  of  189  to  196,  iodine  value  127  to  159,  and  refractive 
index  1-474.  It  is  soluble  in  benzene,  chloroform,  ether, 
and  carbon  disulphide,  and  is  used  in  soap-making. 

Shark  Oil  is  of  much  the  same  character  as  seal  oil,  but 
is  yellow  to  reddish-brown  in  colour,  and  is  used  not  only 
in  soap-making,  but  also  in  paint  manufacture  and  for 
currying  leather. 

Sperm  or  Whale  Oil  comes  from  the  blubber  of  Balana 
mysticetus  and  other  species ;  is  yellowish-brown,  of  sp.  gr. 
about  0-925,  having  a  saponification  value  of  188  to  193  and 
iodine  value  120.  It  is  soluble  in  alcohol  and  ether,  has  a 
strong  fishy  odour,  and  is  used  in  soap-making,  for  lubricat- 
ing, and  as  a  leather  dressing. 

Tuna  Oil  (tunny-fish  oil)  is  pale  yellow  to  red-brown  in 
colour,  and  is  expressed  from  the  livers  of  Thynnus  vulgaris. 
It  has  an  iodine  value  of  about  156,  is  soluble  in  alcohol, 
ether,  etc.,  and  is  used  in' paint-making,  etc. 

Other  varieties  of  fish  oils  are  those  called  Black-fish, 
Halibut,  and  Salmon  Oils. 

A  characteristic  fatty  acid  of  the  fish- oil  group  is  the 
substance  named  clupanodonic  acid,  which  occurs  in  the 
mixed  fatty  acids  obtained  from  Japanese  sardine  oil, 
herring  and  whale  oils,  etc.  It  is  a  pale  yellow  liquid  of 
fishy  odour,  which  readily  oxidizes  on  exposure  to  the  air 
to  a  varnish-like  mass.  (See  Oils.) 

FIXED  OILS— See  Oils. 

FLAME — Gas  in  a  state  of  illumination  (incandescence)  pro- 
duced by  great  heat.  (See  Light  and  Burners.) 

FLAME  COLOURATION — Many  chemical  compounds  com- 
municate distinct  colouration  to  an  otherwise  colourless  or 
nearly  colourless  flame,  such  as  that  of  the  blow-pipe  or 
Bunsen  burner.  (See  Spectroscope.) 


FLA  ME  COLO  URA  TION—FLA  VONE 


201 


brick-red 
green 
red 
white 


FLAME  COLOURATION  (Continued)— 

Potassium  salts  give  a  lilac  colour  to  the  flame. 
Sodium  yellow 

Calcium 
Barium 
Strontium 
Magnesium 
Copper 

Lithium  brilliant  crimson  colour  to  the  flame. 

Lead,   arsenic,   and  antimony  compounds    give    a    bluish-white 
colour  to  the  flame. 

FLASH-POINT  is  the  temperature  at  which  an  oil  or  other 
combustible  fluid  gives  off  vapour  which  will  then  fire  if 
exposed  to  a  naked  light.  The  appliance  used  in  this 
country  for  determining  flash-points  is  one  known  as  Abel's, 
but  on  the  Continent  another  one  named  Pensky's  is  used. 

FLASKS  are  glass  vessels  of  varying  shapes  for  holding 
liquids,  consisting  of  a  body  part  with  flattened  bottom, 
and  a  neck  which  can  be  easily  grasped  by  the  hand  or 
held  by  a  clamp,  and  closed  with  a  cork  when  required. 
The  glass  of  which  they  are  made  is  of  a  quality  to  permit 
the  contents  to  be  heated  (as  when  placed  on  a  sheet  of  wire 
gauze  over  a  lamp  or  on  a  heated  sand-bath)  to  the  tem- 
perature of  boiling  water.  (See  Aspirator  and  Gas  Gene- 
rators.) 

Erlenmeyer  Flask — A  glass  flask  of  the  "conical"  type, 
having  a  flat  bottom  of  diameter  equal  to  from  half  to 
three-quarters  of  its  height,  and  with  side  surface  tapering 
smoothly  from  that  base  to  the  bottom  of  the  neck,  which 
is  short,  narrow,  and  straight-sided. 

These  flasks  have  the  advantage  of  being  more  easily 
washed  out  than  round  flasks,  but  they  are  somewhat  more 
liable  to  crack  on  heating. 

FLAVIN — A  yellow  dyestuff  imported  from  the  United  States 
of  America  (possibly  identical  with  quercitrin),  imperfectly 
soluble  in  water.  (See  Quercitrin.) 

FLAVONE  (C15H10O2)— The  parent  substance  of  a  number  of 
yellow  dyes  found  in  the  vegetable  kingdom,  many  of  which 
occur  in  the  form  of  glucosides. 

The  flavone  family  is  usually  divided  into  "flavone" 
and  "  flavonal  "  compounds,  and  there  appears  to  be  a 
genetic  relationship  between  the  flavone  and  anthocyanin 
series  of  bodies,  inasmuch  as  cyanidin  can  be  produced 
from  quercitrin  by  a  reduction  process.  (See  Plant  Colour- 
ing Matters.) 


202  FLAX— FLUORINE 

FLAX  (Linum  usitatissimum)  is  a  plant  extensively  grown  in 
Ireland,  Belgium,  France,  Russia,  and  other  countries  for 
sake  of  the  fibre  (which  is  the  raw  material  of  linen), 
the  linseed  oil  which  is  extracted  from  it,  and  the  residual 
cake  which  is  used  for  cattle  food.  It  contains  from 
32-77  to  38-42  per  cent,  of  fat,  and  from  3-33  to  5-29  per 
cent,  nitrogen.  (See  Linseed  Oil.) 

FLINT — A  variety  of  quartz.     (See  Silica.) 

FLOTATION  OILS  AND  PROCESS— See  Ores  (treatment). 

FLUELLITE — A  native  fluoride  of  aluminium. 

FLUOR  (Fluorspar)— See  Fluorine. 

FLUORAPATITE— A  mineral  of  composition  3P2O8Ca3,CaF2. 

FLUORESCEIN  (Resorcinol-phthalein)  (C20H12O5  +  H2O)  is 
a  dark  red,  crystalline  powder,  soluble  in  alcohol  to  a 
yellow-red  colour,  and  in  alkalies  to  a  red  colour,  showing  a 
fine  green  fluorescence.  It  is  easily  reduced  to  fluoreecin, 
of  which  the  potassium  salt  is  the  magnificent  dye  eosin. 

All  these  substances  are  extensively  used  in  the  dyeing 
industries.  (See  Eosin.) 

FLUORESCENCE — The  property  of  producing  opalescent  colour 
or  bloom  different  from  that  of  the  liquid  or  substance 
which  exhibits  it.  Green  crystals  of  fluorspar  give  blue  re- 
flection, and  quinine  sulphate  solution  is  strongly  fluorescent. 

FLUORINE  (Fl) — Atomic  weight,  19.  Fluorine  is  found  in 
nature  combined  with  calcium  in  the  mineral  fluorspar 
(CaF2)  (also  known  as  Derbyshire  spar)  and  is  a  constituent 
of  cryolite  (Na3AlF6) — a  double  fluoride  of  sodium  and 
aluminium  found  in  Colorado  and  Greenland  —  and  other 
minerals.  It  is  also  present  in  small  quantities  in  bones 
and  the  enamel  of  teeth. 

Fluorine  can  be  obtained  in  quantity  by  the  electrolysis 
of  fused  potassium  hydrogen  fluoride  or  of  anhydrous 
hydrofluoric  acid  at  —  23°  C.,  and  is,  at  ordinary  tempera- 
tures, a  pale  yellowish  gas  of  very  active  chemical,  corrosive, 
and  poisonous  qualities,  which  attacks  glass  with  avidity, 
but  is  insoluble  in  water.  When  cooled  to  a  temperature 
of— 187°  C.  it  condenses  to  the  liquid  state  in  the  form  of 
a  mobile  yellow  fluid  with  a  characteristic  odour  something 
like  that  of  chlorine,  and  at  a  still  lower  temperature  it 
assumes  the  solid  form  and  is  almost  white. 

Fluorine  acts  strongly  upon  all  metals,  even  gold  and 
platinum  to  some  extent,  and  many  of  them  pass  into  a  state 
of  inflammation  when  thrown  in  a  finely  divided  state  into 
the  gas.  It  also  attacks  organic  substances  with  violence,. 


FLUORINE— FLUX  203 

FLUORINE  (Continued)— 

A  combination  with  hydrogen  known  as  hydrofluoric  acid 
gas  (HF)  is  made  by  warming  a  mixture  of  strong  sul- 
phuric acid  and  powdered  calcium  fluoride  in  a  leaden  or 
platinum  vessel : 

CaF2  +  H2S04  =  CaS04  +  2HF. 

It  is  very  soluble  in  water,  and  is  largely  employed  for 
etching  purposes,  as,  for  example,  making  the  graduations 
on  glass  measuring  apparatus.  The  object  to  be  marked 
in  this  way  is  coated  with  melted  wax,  and  after  making 
the  design  or  marks  on  the  coated  glass,  it  is  exposed  to 
the  action  of  the  acid  either  in  the  form  of  gas  or  liquid, 
with  the  result  that  the  glass  is  eaten  into  where  exposed 
by  the  markings,  the  fluorine  having  no  action  on  the  wax. 

For  some  commercial  purposes,  an  aqueous  solution  of  this 
acid  of  60  per  cent,  strength  is  produced.  Hydrofluoric  acid 
vapour  is  irritating  and  injurious  to  the  respiratory  organs, 
and  the  liquid  produces  ulcerated  sores  on  the  skin,  and  is 
altogether  a  very  dangerous  chemical  compound. 

There  are  fluorides  corresponding  to  the  chlorides  and 
also  a  number  of  double  fluorides.  The  fluorides  of 
potassium,  sodium,  and  iron  are  but  sparingly  soluble  in 
water,  while  the  fluorides  of  silver  and  tin  are  easily  soluble. 
Most  of  the  fluorine  compounds  are  easily  fusible,  and  when 
ignited  in  a  current  of  steam  many  of  them  are  converted 
into  oxides  and  hydrofluoric  acid  is  evolved. 

FLUORSPAR  or  FLUORITE  occurs  in  blue  and  green  forms, 
and  sometimes  consists  of  99-5  per  cent,  calcium  fluoride 
(CaF2).  The  fluorspar  production  in  this  country  amounted 
in  1918  to  53,498  tons,  of  which  30,000  tons  were  used  for 
fluxing  purposes  and  in  the  glass  industry. 

FLUX — A  substance  or  mixture  used  to  assist  fusion  by  heat. 
One  such  flux  is  a  mixture  of  nitre  and  tartar,  and  it  is  either 
placed  in  the  crucible  in  which  the  mineral  is  to  be  fused, 
or  gradually  introduced.  The  oxygen  of  the  nitre  causes 
the  combustion  of  the  carbon  of  the  tartar  and  assists  to 
raise  the  temperature  of  the  mass.  Potassium  cyanide  and 
other  chemicals  are  used  as  fluxes  according  to  the  nature 
of  the  mineral  or  other  substances  to  be  fused. 

Black  flux  is  a  mixture  of  potassium  or  sodium  carbonate, 
sodium  nitrate,  and  carbon,  used  in  assaying ;  and  white 
flux  is  a  mixture  of  sodium  carbonate  with  sodium  nitrate 
and  sodium  nitrite  used  in  metallurgy  and  welding. 


204  FOCUS-FOODS 

FOCUS — The  point  at  which  the  rays  of  light  come  together 
after  passing  through  a  convex  lens. 

FOIL,  or  a  very  thin  sheet  of  metal,  finds  frequent  use  at  the 
hands  of  the  chemist.  Platinum  foil  is  particularly  useful, 
inasmuch  as  it  is  not  acted  upon  by  most  chemicals  and 
withstands  exposure  to  high  temperatures.  It  is  conse- 
quently employed  to  test  the  behaviour  of  solid  substances 
when  exposed  in  crystal  or  powder  form  to  heat  varying 
from  mere  warming  up  to  redness.  For  this  purpose  it  is 
held  by  tongs  or  forceps. 

If,  for  instance,  a  small  quantity  of  crystallized  borax 
(Na2B4O7ioH2O)  be  placed  on  a  piece  of  platinum  foil  and 
heated  over  a  Bunsen  flame,  it  will  be  seen  to  swell  up, 
lose  its  water  of  crystallization,  and  finally  fuse  to  a  clear 
glass-like  appearance. 

Lead,  copper,  tin,  zinc,  aluminium,  and  magnesium  are 
also  prepared  in  the  form  of  foil,  and  are  required  from 
time  to  time  in  the  laboratory. 

FOODS  are  the  other  substances  which,  in  addition  to  water 
and  air  (both  of  which  are  also  essential  to  life),  serve  to 
repair  the  various  tissues  of  the  body  and  to  renew  its 
energy.  They  are  generally  classified  under  the  headings 
of  proteins  (albuminoid  matters),  carbohydrates  (starch, 
sugar,  etc.),  and  fats,  although  vegetable  acids  and  mineral 
salts  are  essential  to  a  perfect  dietary,  as  also  a  small 
quantity  of  the  mysterious  substances  called  hormones 
(which  are  secreted  in  the  body  by  certain  glands)  and 
vitamines.  (See  Vitamines.)  Tea,  coffee,  and  alcohol  are 
often  regarded  as  mere  stimulants  or  accessories,  but  while 
tea  and  coffee  may  be  so  viewed,  alcohol  is  a  real  food 
when  taken  in  moderation,  all  of  it  being  consumed  in 
the  body  and  serving  to  replace  so  much  other  food. 

It  is  usual  nowadays  to  calculate  food  values  in  terms 
of  calories  (heat  units),  a  kilo-calorie  being  the  quantity  of 
heat  sufficient  to  raise  a  kilogramme  (1,000  c.c.)  of  water 
one  degree  Centigrade,  and  it  is  reckoned  that  proteins  and 
carbohydrates  each  produce  4*1  calories  for  every  gramme 
consumed  as  against  9-3  calories  for  each  gramme  of  fat 
consumed. 

A  committee  of  the  Royal  Society  reported  during  the 
recent  war  that  each  man  engaged  in  active  work  requires 
per  day  100  grms.  or  3^  ozs.  protein  (albuminoids),  100  grms. 
or  3!  ozs.  fat,  and  500  grms.  or  17^  ozs.  carbohydrates, 
totalling  approximately  3,400  calories  per  man  per  day. 
In  this  connection  it  should  be  remembered  that  fats  and 


FOODS— FORCE 


205 


FOODS  (Continued)— 

carbohydrates  are  to  some  extent  interchangeable  and  both 
are  similarly  interchangeable  with  alcohol  to  some  degree. 

Taking  the  five  pre-war  years  the  following  table  gives 
the  quantities  in  metric  tons  (2,205  Iks.)  of  tne  total  foods 
imported  and  home  produced : 


Energy 

Amounts. 

Protein. 

Fat. 

Carbo- 
hydrate. 

Value. 
Millions  of 

Calories. 

Metric 

Metric 

Metric 

Metric 

Tons. 

Tons. 

Tons. 

Tons. 

Cereals       

4,865,000 

549,000 

63,000 

3,628,000 

17,712,000 

Meat           

2,685,000 

356,000 

799,000 

— 

8,890,000 

Poultry   and    eggs, 

331,000 

42,000 

3I,OOO 

— 

461,000 

game  and  rabbits 

Fish            
Dairy  produce  (in- 

848,400 
5,231,800 

91,000 
199,000 

17,000 

686,000 

258,000 

531,000 
8,253,000 

cluding  lard  and 

margarine) 

Fruit           

1,271,000 

9,000 

14,000 

222,OOO 

1,077,000 

Vegetables 

5,482,000 

120,000 

10,000 

1,031,000 

4,8l2,OOO 

Sugar      (including 

1,657,000 

5,000 

18,000 

1,572,000 

6,633,000 

cocoa  and  choco- 

late) 

Cottage    and    farm 

— 

67,000 

13,000 

551,000 

2,655,000 

produce    not    in- 

cluded above 

Total  

— 

1,438,000 

1,651,000 

7,262,000 

51,024,000 

Grms. 

Grms. 

Grms. 

Calories. 

Per  head  per  day  ... 

— 

87 

IOO 

44° 

3,091 

Per  "  man  "  per  day 

— 

H3 

130 

571 

4,009 

(See  Gastric  Juice,  Chyle,   Chyme,  Bile,  and  Pancreatic 
Juice.) 

FORCE — Matter  and  force  are  inseparable.  Indeed,  it  may  be 
said  that  the  different  kinds  of  matter  owe  their  phases  to 
the  forces  that  rule  their  existence.  They  are  not  separable : 
there  is  no  force  without  matter,  and  no  matter  without  force. 
A  metal  wire  is  affected  by  and  conducts  the  electric 
current ;  a  strip  of  metal  conducts  the  heat  to  which  it  may 
be  exposed,  from  one  end  to  the  other.  It  is  through  the 
medium  of  the  matter  filling  the  spaces  between,  that  the 
light  from  the  sun  and  the  moon  is  conveyed  to  the  earth. 
The  space  between  a  magnet  and  iron  filings  placed  upon 


206  FORCE 

FORCE  (Continued)— 

a  sheet  of  paper  acts  as  the  medium  of  the  magnetic  force 
from  the  magnet  to  the  iron  filings,  as  evidenced  by  the 
iron  filings  following  the  magnet  when  moved  from  one  to 
another  part  of  the  paper. 

When  a  wire  of  magnesium  metal  is  strongly  heated  in 
the  air,  it  burns  with  an  intense  white  light,  and  through 
the  space  between,  the  light  from  the  burning  metal  is 
conveyed  to  the  eyes. 

Force,  like  matter,  is  indestructible  and  unchangeable 
except  as  to  its  form  or  variety. 

Just  as  matter  can  be  made  to  change  its  form  or  character 
and  properties,  so  force  can  be  made  to  change  its  form 
and  character. 

Heat  can  be  changed  into  light ;  light  can  be  transformed 
into  heat ;  electricity  can  be  changed  into  heat ;  and  all 
may  be  converted  into  mechanical  action  or  power. 

Matter  may  be  defined  as  consisting  of  an  indefinite 
number  of  recognizable  entities,  and  the  distinct  characters 
or  properties  by  which  we  recognize  the  many  varieties  are 
the  expressions — meaning  thereby,  their  appearances,  pro- 
perties, and  their  relations  to  other  substances — given  to 
them  by  the  forces  which  control  them. 

Sugar  is  a  so-called  carbohydrate,  consisting  of  carbon 
in  combination  with  the  elements  of  water,  and  if  strong 
sulphuric  acid  (oil  of  vitriol)  be  allowed  to  fall  upon  a  lump 
of  sugar  and  warmth  applied,  a  great  chemical  change 
rapidly  occurs.  The  strong  acid  seizes  upon  the  water 
elements  (forming  part  of  the  sugar)  with  tremendous 
avidity,  and  the  carbonaceous  part  of  the  sugar  is  set  free 
in  the  form  of  a  black  mass.  Some  of  the  water  thus 
seized  by  the  acid  is  evaporated  owing  to  the  great  heat 
that  is  given  off  in  the  chemical  interaction.  Now,  where 
does  the  heat  come  from  ?  Both  the  sugar  and  the  acid 
are  only  warm  to  start  with,  yet  directly  they  meet  great 
heat  is  given  off.  It  must  come  from  the  forces  which  are 
locked  up  in  the  sugar  and  the  acid.  What  becomes  of 
this  heat  ?  Some  of  it  causes  the  evaporation  of  the  water 
(given  off  as  steam)  which  the  acid  takes  out  of  the  sugar ; 
another  part  is  radiated  through  the  air,  for  the  heat  can  be 
felt.  In  any  case,  heat  is  lost  to  what  was  originally  a 
mixture  of  sugar  and  acid.  In  other  words,  there  is  a  dis- 
sipation of  energy  in  the  form  of  heat  from  forces  that  were 
in  some  way  locked  up  in  the  two  varieties  of  matter  which 
when  placed  in  contact,  underwent  chemical  change  attended 
with  the  results  here  described. 


FORCE  207 

FORCE  (Continued)— 

So,  again,  in  the  burning  of  a  wire  of  magnesium  metal 
in  the  air,  not  only  is  great  heat  given  off,  but  also  much 
bright  light,  showing  that  magnesium  and  oxygen  do  not 
consist  of  mere  matter  as  something  distinct  from  force,  but 
that  they  are,  like  all  other  substances,  compounded  of  the 
two  things.  (See  Matter.) 

Mechanical  force  is  capable  of  bringing  about  certain 
chemical  changes.  For  example,  a  mixture  of  potassium 
chlorate  and  sulphur  enters  into  chemical  action  with 
explosive  violence,  when  placed  upon  a  hard  surface,  as 
of  iron  or  stone,  and  hit  with  a  hammer,  or  when  rubbed 
together  with  a  pestle  in  a  mortar.  It  may  be,  however, 
that  in  such  cases,  the  energy  or  the  friction  causes  the 
local  emission  of  heat,  as  in  the  striking  of  matches,  and 
that  the  heat  thus  developed  is  the  immediate  cause  of  the 
chemical  changes  that  are  induced. 

Again,  a  mixture  of  hydrochloric  acid  and  phosphine 
(phosphoretted  hydrogen)  gases,  when  exposed  to  pressure, 
undergoes  chemical  combination,  and  there  is  produced  a 
solid  crystalline  substance  known  as  phosphonium  chloride 
(PH4C1).  The  same  compound  is  produced  also  by  pass- 
ing the  mixed  gases  through  a  tube  immersed  in  a  freezing 
mixture,  and  it  is  again  dissociated  into  the  originating 
substances  when  exposed  to  the  air  under  normal  pressure. 

Force  takes  a  part  in  every  chemical  change,  but  this 
part  is,  unfortunately,  not  revealed  by  the  symbolic  equa- 
tions used  by  chemists  to  represent  the  more  material  sides 
of  these  changes.  For  example,  the  equation 

SO3  +  H20  =  H2SO4 

expresses  the  formation  of  sulphuric  acid  by  a  combination 
of  sulphuric  anhydride  and  water,  but  it  does  not  reveal  the 
fact  that  the  combination  involves  an  expenditure  of  energy 
disengaged  as  heat,  sufficient  to  raise  the  temperature  of 
213  grammes  or  cubic  centimetres  of  water  from  o°  to  its 
boiling-point — 100°  C. 

A  mass  of  772  pounds  falling  through  i  foot  of  space 
produces  by  friction  sufficient  heat  to  raise  the  temperature 
of  i  pound  of  water  i°  F. 

When  water  is  changed  into  ice,  a  certain  amount  of 
heat  is  evolved,  and,  on  the  other  hand,  when  water  is 
changed  into  steam  a  larger  amount  of  heat  is  absorbed. 

Again,  when  nitrogen  trichloride  is  suddenly  heated,  it 
explodes  with  great  violence  and  is  resolved  into  its  elements, 


208  FORCE— FORMALIN 

FORCE  (Continued)— 

and  in  this  change  a  tremendous  amount  of  energy  is  used 
up  in  overcoming  the  atmospheric  pressure  which  acts  as  a 
restraining  influence. 

So  it  is  with  every  chemical  change.  The  energy  that  is 
expended  may  reappear  as  light  or  electrical  force,  or  in 
what  is  commonly  regarded  as  its  lowest  degraded  form — 
viz.,  heat ;  but  there  is  no  absolute  destruction  or  annihila- 
tion of  force.  All  matter  being,  as  it  were,  made  up  of 
substance  and  force,  there  is  a  redistribution  but  no  loss  of 
either  when  undergoing  chemical  change. 

That  the  recent  investigations  concerning  the  atomic 
structure  of  chemical  entities  will  lead  to  the  conclusion 
that  all  the  forms  of  matter  are  to  be  ascribed  to  move- 
ments of  the  ultimate  particles  of  two  primordial  elements 
in  the  nature  of  positive  and  negative  electricity  is  not  at 
all  clear  and  cannot  be  accepted  until  the  nature  of  the 
nuclei  of  the  atoms  has  been  definitely  ascertained.  It  is 
far  more  likely  that  while  there  may  be  oneness  of  ultimate 
matter,  all  its  changes  are  to  be  attributed  to  the  forces, 
whatever  they  may  be,  that  control  it,  determine  all  its 
phases,  and  are  indissolubly  bound  up  with  it.  (See 
Elements  and  Radio-activity.) 

FORMALDEHYDE  or  METHYL  ALDEHYDE  (CH2O)  is 
a  gas  soluble  in  water,  and  a  solution  of  40  per  cent, 
strength  is  an  article  of  commerce,  largely  used  for 
disinfecting  and  preservative  purposes.  It  has  a  very 
irritating  action  on  the  mucous  membranes  of  the  eyes, 
nose,  and  throat.  It  is  made  by  a  contact  action  brought 
about  by  passing  a  current  of  methyl  alcohol  vapour  admixed 
with  air  over  a  glowing  platinum  or  copper  spiral,  and 
absorption  in  water,  in  which  solution  it  has  the  hydrate 
formula  CH2(OH)2. 

It  possesses  the  property  of  making  gelatine  in  any  form 
insoluble  in  water,  and  this  is  utilized  in  many  technical 
applications,  including  the  preservation  of  adhesives  and 
anatomical  specimens.  It  is  also  used  in  the  processes  of 
making  bakelite  and  other  allied  articles. 

The  polymeric  solid  white  paraform  is  more  useful 
for  disinfecting  rooms  by  fumigation,  as  it  is  easily  vaporized 
and  is  equally  effective  per  unit  of  active  agent. 

Formaldehyde  is  believed  to  play  an  important  part  in 
the  process  of  plant  assimilation. 

FORMALIN — A  commercial  solution  of  40  per  cent,  formalde- 
hyde in  water,  used  as  a  disinfectant. 


FORMA  MIDE— FORMULA  209 

FOEMAMIDE— See  Amides. 

FOEMIC  ACID  (CH2O2)  occurs  naturally  in  ants,  in  stinging- 
nettles,  in  the  processionary  caterpillar,  the  fruit  of  the  soap- 
tree  (Sapindus  saponaria),  in  fir  cones  and  tamarinds,  and  is 
also  formed  as  a  by-product  in  the  atmospheric  oxidation 
of  turpentine.  When  pure,  it  is  a  colourless  liquid  of 
sp.  gr.  i'2i78,  which  solidifies  at-  i°  C.,  and  fumes  in  the 
air.  It  is  a  powerful  antiseptic,  very  corrosive,  and  mixes 
with  water  in  all  proportions.  For  commercial  purposes 
it  is  prepared  of  70  and  80  per  cent,  strengths,  and  finds 
industrial  applications  in  the  textile  and  tanning  trades. 

"  FORMITE  " — A  proprietary  phenol-formaldehyde  product, 
used  as  an  electrical  insulating  material  and  plastic  cement. 
It  is  unaffected  by  oils  and  many  solvents,  and  solutions  of 
it  are  made  up  as  varnishes  for  special  applications. 

FOEMOSE  (C6H12O6)— A  mixture  of  glucoses  obtained  by  the 
action  of  lime-water  on  formaldehyde,  with  which  it  is 
polymeric. 

FOEMUK5! — The  arrangement  of  symbols  representing  the 
chemical  composition  of  substances.  The  symbols  which 
are  used  are  explained  in  the  several  sections  dealing  with 
Chemical  Compounds,  Chemical  Interactions,  and  Elements, 
and  the  formulae  employed  are  of  various  types.  The 
ordinary  formulae  indicate  the  molecular  composition  with- 
out respect  to  any  particular  molecular  arrangement  or 
structure ;  thus  NaCl  expresses  the  combination  of  i  atom 
of  sodium  with  i  atom  of  chlorine  in  i  molecule  of  salt. 
Again,  the  formula  (NH4)2SO4  expresses  the  combination 
of  2  of  the  groups  NH4  with  i  of  SO4  in  i  molecule  of 
ammonium  sulphate,  and  so  forth. 

The  empirical  formula  of  a  substance  is  ascertained  from 
the  results  of  its  analysis,  the  percentages  of  elements  found 
present  being  divided  by  their  atomic  weights.  For  example, 
hydrocyanic  acid  upon  analysis  is  shown  to  contain  as  follows: 

Hydrogen      ...  ...  3704  per  cent. 

Carbon  ...  ...         44'444    »       » 

Nitrogen        ...  ...         51-852    „       „ 

and  if  these  percentages  are  divided  by  the  atomic  weights 
of  the  three  elements — viz.,  H  =  i,  C  =  i2,  and  N=i4 — it 
will  be  found  that  the  quotients  are  practically  identical,  so 
that  the  component  elements  are  combined  in  the  pro- 
portions of  one  each — viz.,  HCN,  which  is  the  simplest 
formula  of  the  substance, 


2 1  o  FORM  ULM—FRA  NKINCENSE 

FORMULAS  (Continued)— 

Or  again,  taking  salt  (sodium  chloride),  it  yields  upon 
analysis  39*31 6  per  cent,  sodium  and  60*684  per  cent, 
chlorine,  and  the  division  of  these  numbers  by  the  atomic 
weights  23  and  35-5  shows  the  two  components  to  be  con- 
tained in  the  elemental  proportions  so  that  the  empirical 
formula  is  NaCl. 

Constitutional  or  Rational  formulae,  on  the  other  hand, 
are  used  to  express  a  sense  of  construction  or  structure,  as 
when,  for  example,  ammonium  cyanate  is  resolved  by 
heating  into  urea,  the  change  may  be  expressed  as  follows : 

CNO(NH4)  =  CO(NH2)2 

in  order  to  show  that,  although  empirically  the  composition 
of  the  two  substances  is  the  same,  being  concretely  ex- 
pressed by  the  formula  CN2H4O,  the  molecular  arrange- 
ments or  structures  are  different. 

Again,  the  empirical  formula  of  ethyl  alcohol  is  C2H6O, 
but  when  expressed  constitutionally  as  C2H5(HO),  it  is  seen 
that  the  molecule  has  an  alcoholic  structure  and  that  the 
group  HO  can  be  replaced  or  substituted  by  other  groups. 
So  again,  acetic  acid  (C2H4O2)  may  be  expressed  constitu- 
tionally in  several  ways,  thus  : 

CH3— C^ 

X)H 

— that  is,  carbon  in  association  with  the  groupings  CH3, 
OH,  and  the  oxygen  atom ;  otherwise  as  CH3,CO,OH — 
that  is,  the  radical  methyl,  the  radical  hydroxyl,  and  oxygen 
all  in  direct  combination  with  the  carbon;  or  as  H(C2H3O2) 
— that  is,  as  hydrogen  acetate  or  a  molecule  of  hydrogen  in 
which  i  atom  is  replaced  by  the  group  C2H3O2,  according 
to  the  views  taken  of  the  structure  of  the  acetic  acid 
molecule. 

FRACTIONAL  DISTILLATION  affords  the  means  of  separ- 
ating, more  or  less,  the  several  constituents  of  mixed  distil- 
lable  liquids,  by  collecting  the  portions  or  fractions  which 
pass  over  at  varying  temperatures.  For  example,  alcohol 
boils  at  78°  C.  and  aniline  at  185°  C.,  so  that  a  mixture  of  the 
two  substances  can  be  separated  by  this  process.  (See  also 
Boiling-point  and  Retort.) 

FRANKINCENSE  (Gum  thus) — An  oleo-resinous  exudation 
from  the  spruce  fir  (Abies  excelsa),  from  which  burgundy 
pitch  is  made  by  melting  and  straining  it  through  a  cloth. 


FRANKLINITE— FULLER'S  EARTH  211 

FRANKLINITE — An  iron-manganese-zinc  ore  found  in  New 
Jersey  and  elsewhere,  having  the  composition  (ZnFeMn)O, 
(FeMn)203. 

FREEZING  MIXTURES  are  employed  by  chemists  to  lower  the 
temperature  at  which  chemical  interactions  may  occur,  and 
there  are  many  kinds  available.  One  of  the  simplest  is  a 
mixture  of  ammonium  nitrate  (NH4NO3)  and  water  in  equal 
parts,  the  dissolving  of  the  salt  causing  a  drop  in  tempera- 
ture from  40°  F.  to  4°  F.  By  the  use  of  a  mixture  of  2  parts 
snow  or  pounded  ice  and  i  part  salt,  a  steady  temperature 
of  -  4°  F.  can  be  maintained ;  while  one  of  2  parts  snow 
and  3  parts  crystallized  calcium  chloride  (CaCl2)  will  bring 
the  temperature  down  from  32°  F.  to  —  50°  F.  (See  Heat.) 

FRENCH  CHALK  (Steatite  or  Soap-stone)— A  soft  silicate  of 
magnesium  mineral,  talc-like  in  nature. 

FRENCH  POLISH — A  solution  of  shellac  in  alcohol,  other 
resins  being  sometimes  incorporated. 

FRIT — The  materials  used  in  compounding  glass  and  enamels 
as  obtained  by  the  baking  or  calcination  of  them,  but 
before  fusion. 

FRUCTOSE  (Laevulose)— A  fermentable  form  of  crystallizable 
fruit  sugar  (CgH^Og)  found  accompanying  glucose  in  the 
juice  of  sweet  fruits  and  in  honey.  It  melts  at  95°  C., 
and  can  be  prepared  from  cane  sugar  by  hydrolysis  with 
hydrochloric  acid.  It  has  also  been  made  from  various 
plant  sources,  including  artichokes.  It  is  soluble  in  water, 
alcohol,  and  ether,  and  is  laevo-rotatory  in  character. 

FRUIT  SUGAR — See  Fructose. 

FUCHSINE  (Roseine) — Another  name  for  magenta,  one  of 
the  aniline  dyes  used  in  the  textile  and  leather  industries. 
(See  Magenta.) 

FUEL  (liquid)— See  Colloidal  Fuel. 

FULLER'S  EARTH — A  natural  porous  and  absorptive  alu- 
minium silicate,  of  greyish,  yellowish,  or  greenish  colour, 
widely  distributed  and  largely  produced  both  in  England 
and  in  the  United  States— a  powerful  absorbent  of  oily 
matters.  At  one  time  it  was  extensively  used  for  "  fulling  " 
clothes,  but  now  it  is  chiefly  employed  in  connection  with 
the  bleaching  and  filtering  of  fats  and  oils,  as  a  carrier  of 
pigments,  the  removal  of  grease  from  woollen  goods,  and  as 
a  toilet  article. 
The  English  supply  of  Fuller's  earth  comes  chiefly 


212  FULLER'S  EARTH— FUMIGATION 

FULLER'S  EARTH  (Continued)— 

from  Surrey  quarries  and  some  Somerset  mines ;  an 
analysis  of  the  Nutfield  earth  showing  58-66  per  cent, 
silica,  17*33  Per  cent-  alumina,  7*21  per  cent,  ferric  oxide, 
3-17  per  cent,  lime,  3-26  per  cent,  magnesia,  1-63  per 
cent,  soda  and  potash,  and  loss  on  ignition  874  per  cent. 

FULMINATING-  GOLD— A  compound  of  auric  oxide  (Au2O3) 
and  ammonia,  of  explosive  character,  the  exact  chemical 
constitution  of  which  has  not  been  ascertained. 

FULMINATING  MERCURY  or  FULMINATE  OF  MERCURY 

(HgC2N2O2) — A  dark  brown,  crystalline  compound  used 
for  priming  percussion  caps  and  in  making  detonators. 
It  explodes  when  dry  under  the  slightest  friction  and  has 
to  be  kept  wet  until  used.  It  is  prepared  by  the  action 
of  strong  nitric  acid  upon  mercury  and  alcohol. 

FULMINATING  SILVER  is  prepared  by  dissolving  silver 
oxide  (Ag2O)  in  strong  ammonia,  and  is  an  explosive  com- 
pound, possibly  of  the  nature  of  a  nitride  (Ag3N). 

FULMINIC  ACID  (HCNO)— Known  chiefly  in  its  combinations 
and  said  to  be  produced  by  the  action  of  sulphuric  acid  on  a 
solution  of  potassium  fulminate  followed  by  extraction  with 
ether.  It  is  the  oxime  of  carbon  monoxide.  See  Oximes. 

FUMARIC  ACID  (C^^OJ  is  a  natural  constituent  of  some 
plants  and  lichens,  including  Fumaria  officinalis,  Glaucium 
flavum,  and  Iceland  moss.  It  crystallizes  in  colourless 
prisms,  is  inodorous,  has  an  acid  taste,  and  is  readily  soluble 
in  hot  water,  alcohol,  and  ether.  It  is  nearly  allied  in  constitu- 
tion to  malic  acid,  and  it  is  resolved  into  succinic  acid  by 
the  action  of  reducing  agents. 

FUMIGATION — Exposure  to  the  action  of  vapours  or  fumes, 
as  when  fumigating  a  room  by  sulphur  dioxide  generated 
from  a  burning  sulphur  candle,  for  the  purpose  of  disin- 
fection. 

A  recent  investigation  has  established  the  fact  that  the 
vapours  of  formaldehyde  and  paraform  have  identically 
the  same  value  as  germicidal  agents  when  used  for  fumiga- 
tion of  rooms,  and  that  the  presence  of  water-vapour  does 
not  facilitate  the  disinfection.  By  the  same  investigation 
it  was  also  proved  that  a  sulphur  candle  of  9  ozs.  weight 
burned  in  association  with  the  avaporation  of  6  ozs.  of 
water,  suffices  to  sterilize  a  room  of  1,000  cubic  feet  capacity 


FUMIGA  TION-FUSION  213 

FUMIGATION  (Continued)— 

within  two  hours,  while  20  grms.  of  paraform  or  if  ozs.  of 
40  per  cent,  solution  of  formaldehyde  are  equally  effective. 

FUMING  SULPHURIC  ACID— See  Nordhausen  Acid  and 
Sulphur. 

FURANE  (Furfurane) — See  Furol. 

FURNACES,  as  used  in  laboratories,  are  of  various  descriptions. 
The  electrical  furnace  is  only  to  be  found  in  highly  equipped 
establishments,  and  some  references  to  its  industrial  applica- 
tions will  be  found  elsewhere.  (See  Electricity,  Heat, 
Reverberating  Furnace,  and  Organic  Analyses.) 

FUROL  or  FURFUROL  (CgH^)  is  a  colourless,  inflammable, 
volatile,  aromatic  oil,  obtained  by  distilling  sugar,  wood,  or 
bran  with  moderately  strong  sulphuric  acid.  It  turns  brown 
upon  exposure  to  the  air,  has  a  sp.  gr.  of  1*1594,  and  boils 
at  162°  C.  It  finds  some  employment  in  the  arts,  and, 
as  prepared  from  corn-cobs,  is  likely  to  be  of  service  in 
the  production  of  synthetic  resins.  It  has  chemical  re- 
lationship to  furfurane,  a  colourless,  mobile  liquid  contained 
in  pinewood  tar,  with  an  odour  something  like  that  of 
chloroform,  and  which  boils  at  32°  C. 

FUSEL  OIL — A  mixed  residue  of  alcohols  of  higher  boiling- 
point  than  ordinary  ethyl  alcohol,  together  with  some 
aldehydes,  esters,  and  other  substances,  including  pelar- 
gonic  and  capric  acids,  left  as  a  by-product  from  the  dis- 
tillation of  alcohol  produced  by  fermentation,  particularly 
that  from  potato  starch.  One  of  its  chief  constituents  is 
isoamyl  alcohol.  It  has  an  unpleasant  odour  and  taste, 
and  it  is  therefore  of  importance  to  remove  it  from  spirits 
intended  for  consumption.  (See  Amyl  Alcohol.) 

FUSIBLE  METAL  —  An  alloy,  the  melting-point  of  which 
largely  depends  upon  the  proportion  of  bismuth  employed, 
generally  about  50  per  cent,  with  lead  about  25  per  cent., 
tin  12  to  13  per  cent.,  and  cadmium  about  12  to  13  per 
cent.  It  has  a  fusing-point  of  67* 5°  C.,  and  is  used  for 
producing  casts  of  metals,  solders,  and  in  making  safety 
valves  for  boilers,  fusible  plugs,  valves,  etc.  (See  Bismuth.) 

FUSION — The  liquation,  or  melting  into  the  fluid  state,  of 
solids  by  means  of  heat.  The  temperatures  at  which  this 
liquation  takes  place  are  called  the  fusing  or  melting  points. 
(See  Liquation  and  Metals.) 


214  FUSTIC  EXTRACT— GALLIUM 

FUSTIC  EXTRACT  (Cuba  wood)  is  the  name  of  a  yellow  dye 
of  two  varieties — viz.,  "old  fustic,"  obtained  from  Morns 
tinctoria  (yellow  Brazil  wood),  and  "young  fustic,"  from 
Rhus  cotinus.  The  colouring  matter  itself  is  named  fustin, 
and  is  used  in  the  textile  and  leather  industries. 

GADOLINITE — A  complicate  silicate  mineral  found  in  Norway 

and  Sweden  (known  also  as  yttrite  and  ytterbyite)  of  black, 

:  brown,  and  yellow  colour,  containing  the  rare  earths  yttria, 

ceria,  etc. ;  also  found  in  pegmatites  in  Arizona,  Colorado, 

and  Texas. 

GADOLINIUM  (Gd)— Atomic  weight,  157-3.  A  very  rare  and 
but  little  known  element  of  the  terbium  group,  found 
present  in  samarskite,  orthite,  cerite,  etc. 

GAHNITE  (Zinc  spinnelle)  —  A  natural  zinc  aluminate 
(ZnO,Al203). 

GALACTOSE  (C6H12O6)  —  A  colourless,  crystalline  carbo- 
hydrate, soluble  in  water  (prepared  by  oxidation  of  dulcitol), 
which  melts  at  about  170°  C. 

GALBANUM — A  resin  imported  from  the  Cape  and  Persia, 
and  reported  to  be  produced  from  the  umbelliferous  plant 
Babon  galbanum  or  Ferula  galbaniflua. 

GALENA— See  Lead. 

"  GALILITH  " — A  product  made  from  casein,  hardened  with 
formaldehyde,  and  used  in  making  buttons  and  cheap 
combs,  etc. 

GALIPOT — A  French  name  for  resin  from  the  Pinus  mavitima. 

GALLIC  ACID  (C7H6O6)  occurs  in  nut  galls,  sumach,  tea,  and 
a  number  of  tannins  in  the  form  of  a  glucoside,  from  which 
it  can  be  made  by  boiling  with  acids.  In  the  pure  state  it 
crystallizes  in  nearly  colourless  silky  needles  of  the  com- 
position C7H6O5,H2O,  which  are  soluble  in  water,  ether, 
and  alcohol.  With  ferrous  sulphate  it  gives  a  brown  colour, 
which  quickly  blackens  on>.  xposure  to  the  air,  and  is  used 
in  photography  and  the  manufacture  of  ink.  (See  Inks.) 

GALLIPOLI — A  crude  olive  oil  used  in  the  textile  industries. 

GALLIUM  (Ga)— Atomic  weight,  69-9;  sp.  gr.,  5-88;  melting- 
point,  2975°  C.  A  rare  metal  occurring  in  very  minute 
amounts  in  certain  specimens  of  zinc  blende  from  the 
Pyrenees.  Little  is  known  about  it  beyond  its  spectro- 
scopic  character.  It  is  a  grey  lustrous  metal  which  com- 


GA  LLI UM—GA  NISTER  2 1 5 

GALLIUM  (Continued}— 

bines  rapidly  with  chlorine,  is  soluble  in  warm  hydrochloric 
and  nitric  acids,  and  forms  an  alloy  with  aluminium.  It 
decomposes  water  at  high  temperatures,  and  its  compounds 
resemble  those  of  aluminium. 

GALL  NUTS  are  produced  as  excrescences  on  the  leaves  (and 
their  stalks)  of  the  oak  (Quercus  infectoria)  by  punctures  of 
gall-wasps,  in  which  they  lay  their  eggs.  The  Aleppo  galls 
are  most  valued,  but  although  those  from  the  Levant  (con- 
taining about  58  per  cent,  tannin)  are  the  best,  there  are 
others  of  inferior  quality  which  come  from  Dalmatia  and 
other  places.  They  contain  tannic  or  gallo-tannic  acid,  which 
is  also  present  in  sumach  and  tea,  and  are  used  in  tanning, 
in  the  manufacture  of  blue-black  ink,  also  for  the  pro- 
duction of  certain  tints  in  Turkey-red  dyeing  and  in  calico- 
printing.  (See  Inks.) 

GALLO-TANNIC  ACID— A  colourless,  amorphous  substance 
found  in  nut  galls  (gall  nuts),«etc.,  which  has  been  credited 
with  the  formula  C21H22O17  (Strecken),  and  regarded  as  a 
compound  of  grape  sugar  and  gallic  acid  in  the  molecular 
proportion  1:3;  but  it  has  more  recently  been  proved  to 
be  a  sugar  ester  of  complex  formula,  and  it  is  claimed  to 
have  been  synthesised.  (See  Tannic  Acid.) 

GALVANISM— See  Electricity. 

GALVANIZING — Iron  coated  with  zinc  by  immersion  in 
molten  zinc,  after  suitable  preparation  by  cleansing,  etc. 
Cold  galvanizing  is  stated  to  be  carried  on  commercially  by 
the  electrolysis  of  zinc  sulphate  solution,  using  a  zinc  anode. 
It  has  been  computed  that  one-half  of  the  total  zinc 
production  is  used  in  galvanizing. 

GAMBLER — The  inspissated  juice  of  an  Indian  plant  (Uncaria 
gambier),  which  grows  also  in  Malacca,  and  is  largely  used 
in  dyeing  and  tanning.  It  is  principally  imported  from 
Singapore. 

GAMBOGE — A  gum  resin  from  the  Stalagmites  cambogioides  tree 
which  grows  in  Cambogia  (Siam).  It  acts  as  a  drastic 
purgative,  but  as  prepared  in  cakes  for  the  market  it  is 
chiefly  used  as  a  pigment  for  water-colour  painting. 

GANGUE— The  mineral  matter  enclosing  or  intimately  asso- 
ciated with  metallic  and  other  ores. 

GANISTER — A  highly  refractory  siliceous  sedimentary  rock, 
used  for  lining  blast  and  other  furnaces. 


2i6  GARNET— GAS 

GARNET — Name  of  a  variety  of  crystalline  minerals  (almandite, 
andvatite,  essonite,  etc)  of  varying  colours,  consisting  of 
double  silicates  of  various  bases,  including  alumina. 

GARNIERITE — A  hydrated  silicate  of  nickel  and  magnesium. 
(See  Nickel.) 

CKAS  (Coal) — The  composition  of  coal  gas  as  produced  for 
illuminating  purposes  depends  very  largely  upon  the  tem- 
perature at  which  the  roasting  of  the  coal  takes  place,  and 
upon  the  amount  of  air  that  gains  access  to  the  retorts.  It 
contains  not  only  permanent  gases  but,  in  addition,  con- 
siderable quantities  of  the  vapours  of  volatile  hydrocarbons, 
to  which  its  luminosity  in  burning  is  due.  The  greater 
proportion  consists  of  hydrogen  (about  35  to  50  per  cent.), 
which  burns  with  a  practically  colourless  flame,  and  marsh 
gas  or  methane  (CH4)  (about  35  to  40  per  cent.),  which  also 
gives  but  little  light  when  burned  alone.  Accompanying 
these  constituents  there  are  proportions  of  carbon  dioxide, 
carbon  monoxide,  nitrogen,  and  oxygen. 

The  illuminating  power  of  coal  gas  is  chiefly  attributable 
to  olefiant  gas  and  other  associated  hydrocarbons,  which, 
in  all,  amount  to  about  5  per  cent.,  and  the  process  of 
roasting  the  coal  is  conducted  in  such  a  way  as  to  yield 
about  10,000  cubic  feet  of  gas  per  ton  of  coal. 

In  1913,  about  twenty  million  tons  of  coal  were  carbonized 
in  the  United  Kingdom  for  the  manufacture  of  coal  gas. 

The  composition  of  good  coal  gas  according  to  one 
analysis,  which  is  fairly  representative,  is  as  follows : 

Hydrogen  ...  ...  ...  48-2  per  cent. 

Methane  ...  ...  ...  34*2     „       „ 

Carbon  monoxide  ...  ...  6*6    „       „ 

Olefines  and  benzene        ...  ...  5-3     „       „ 

Nitrogen,  carbon  dioxide,  and  oxygen  57    „       „ 

loo-o 

The  gas,  however,  now  supplied  in  many  places  consists 
of  a  mixture  of  ordinary  coal  gas  with  so-called  water  gas, 
or  carburetted  water  gas — that  is,  the  mixture  of  carbon 
monoxide  and  hydrogen  which  is  produced  by  passing 
steam  over  red-hot  coke,  while  at  the  same  time  a  certain 
quantity  of  petroleum  is  introduced  and  destructively  de- 
composed or  "  cracked  "  in  the  furnace,  to  give  to  the  other 
gases  that  proportion  of  hydrocarbons  necessary  to  give  lumin- 
osity to  the  whole  mixture  when  it  is  burned.  (See  Coal.) 


GASES 


217 


GASES— In  addition  to  the  recently  discovered  rare  elements 
contained  in  the  air,  five  of  the  better  known  ones  exist 
ordinarily  in  the  gaseous  state — viz.,  hydrogen,  oxygen, 
nitrogen,  chlorine,  and  fluorine. 

Gases  vary  greatly  in  their  general  properties,  being 
of  varying  colours  (although  mostly  colourless),  densities, 
solubilities  in  different  fluids,  and  chemical  affinities. 
They  can  all  be  reduced  to  the  liquid  or  solid  state  by 
lowering  the  temperature  and  increasing  the  pressure 
sufficiently,  and  the  highest  temperature  at  which  a 
gas  can  be  liquefied  by  pressure  is  called  its  "critical 
temperature,"  while  the  "critical  pressure"  is  that 
under  which  it  can  be  liquefied  at  its  critical  tempera- 
ture. Many  gases  are  readily  absorbed  by  charcoal,  and 
some  of  them  are  occluded  by  metals.  (See  Palladium 
and  Occlusion.)  Recently  heated  beechwood  charcoal  will 
absorb  by  what  is  called  "  surface  action  "  (see  Adsorption) 
90  times  its  own  volume  of  ammonia,  while  that  from 
cocoa-nut  shell  will  take  up  171  volumes.  The  gases  most 
easily  liquefied  are  those  which  are  most  readily  absorbed 
by  charcoal,  and  in  this  condensed  (or  maybe  partially 
liquefied)  form  they  exhibit  unusually  active  chemical  pro- 
perties. For  example,  powdered  charcoal  saturated  with 
hydrogen  sulphide  when  brought  into  contact  with  oxygen, 
bursts  into  combustion  owing  to  the  rapid  chemical  action 
of  the  two  gases. 

All  gases  tend  to  expand  and  the  pressure  or  elastic  force 
of  a  gas  is  the  collective  effect  of  the  bombardment  of  its 
freely  moving  molecules  against  the  containing  vessel. 

A  list  of  the  critical  temperatures  and  pressures  and 
boiling-points  of  the  better  known  gases  is  appended : 


Gas. 

Critical 
Temperature. 

Critical 
Pressure  : 
Atmospheres. 

Boiling-point 
under  760  mm. 
Pressure. 

Ammonia 

132-9°  C. 

1  12-3 

-  33-46°  c. 

Carbon  dioxide 

3l'0° 

72-9 

-    80'0° 

Chlorine 

141-0° 

83-9 

-   337° 

Hydrogen 

-241-0° 

19-4 

-252-5° 

Nitrogen 

~  145-0° 

33-6 

-  195-5° 

Oxygen 

-118-8° 

50-8 

-182-9° 

Sulphur  dioxide 

157-2° 

777 

-    10-1° 

218  GASES— GAS  GENERATORS 

GASES  (Continued)— 

Equal  volumes  of  gases  at  the  same  temperature  and 
pressure  contain  an  equal  number  of  molecules,  and  the 
volume  occupied  by  a  given  weight  of  any  gas  is  inversely 
as  the  pressure. 

The  densities  of  the  gaseous  elements  are,  for  the  most 
part,  identical  with  their  atomic  weights  (phosphorus  and 
arsenic  are  two  of  the  most  noticeable  exceptions,  their 
vapours  possessing  a  density  twice  as  great  as  that  re- 
quired by  the  general  law). 

The  densities  of  compound  gases  are  one-half  of  their 
molecular  weights.  (See  Vapour  Densities.) 

One  litre  of  hydrogen  at  o°  C.  and  760  mm.  mercury 
weighs  0-08936  grm.,  and  the  weights  of  litres  of  other 
gaseous  elements  are  ascertained  by  multiplying  this  factor 
by  their  atomic  weights. 

Gases  expand  ^|^  part  of  their  volume  at  o°  C.  for  every 
increase  of  i°  C.  in  temperature  at  constant  pressure. 

Gases  exhibit  a  peculiar  property  of  diffusion,  so  that  if 
two  vessels  containing,  say,  oxygen  and  hydrogen  respec- 
tively, be  placed  with  their  openings  in  contact,  each  gas 
will  mingle  with  the  other  so  thoroughly  and  automatically, 
that  after  a  time,  there  is  uniformity  of  composition  of  the 
gases  contained  in  the  several  vessels.  It  has  been  ascer- 
tained that  the  relative  velocities  of  diffusion  of  any  two 
gases  are  inversely  as  the  square  roots  of  their  densities. 
This  diffusion  is  readily  appreciated  if  it  be  borne  in  mind 
that  gaseous  matter  is  to  be  regarded  as  an  aggregation  of 
molecules  in  which  the  attractive  force  which  unites  them  is 
reduced  to  a  minimum  because  the  spaces  they  occupy  are 
relatively  great,  and  that  these  molecules  are  therefore  in  a 
constant  state  of  rapid  motion  and  bombardment — a  state 
of  things  that  is  of  course  greatly  enhanced  by  the  applica- 
tion of  heat.  It  is  this  bombardment  that  is  the  foundation 
of  the  pressure  or  elastic  force  exercised  by  gas  confined  in 
a  vessel  at  any  given  temperature  and  pressure.  (See 
Molecules.) 

GASES  (Diffusion  of)— See  Gases  and  Diffusion. 
GASES  (Liquefaction  of)— See  Heat. 
GAS  BURNERS— See  Burners. 

GAS  GENERATORS— There  are  many  forms  of  laboratory  gas 
generators,  bottles  and  flasks  properly  fitted  up  being  often 
employed,  and  particularly  the  latter  when  it  is  necessary 
to  employ  the  agency  of  heat. 


GAS  GENERATORS— GAS  MANTLES 


219 


GAS  GENERATORS  (Continued)— 

Kipp's  apparatus  for  the  generation  of  hydrogen  disulphide 
(sulphuretted  hydrogen),  carbon  dioxide,  etc.,  in  gaseous 
form,  is  of  glass,  and  consists 
of  sections  as  shown  in  figure, 
the  upper  part,  which  is  re- 
movable, terminating  in  a  long 
tube  which  passes  down 
through  the  middle  one  and 
reaches  near  the  bottom  of  the 
lower  one.  To  make  hydro- 
gen disulphide,  iron  sulphide 
in  small  lumps  is  placed  in 
the  glass  reservoir  B,  and 
concentrated  hydrochloric  acid 
poured  into  A  by  means  of 
the  thistle  funnel  and  tube 
fitted  into  its  neck  until  C  is 
filled  and  the  acid  rises  to 
some  extent  into  B,  where  it 
acts  on  the  iron  sulphide, 
liberating  hydrogen  disulphide. 
The  gas  can  now  be  obtained 
by  opening  the  cock  E,  and 
then  it  passes  out  at  F.  When 
not  required,  the  cock  is  shut,  and  the  gas  generated  in 
B  then  exerts  pressure  on  the  acid  left  in  it,  and  forces 
it  down  into  C  and  up  into  A,  thus  leaving  the  iron  sulphide 
and  the  aid  out  of  contact,  gas,  therefore,  ceasing  to  be 
generated. 

When  it  is  desired  to  use  this  apparatus  for  the  genera- 
tion of  carbon  dioxide,  lumps  of  marble  (CaCO3)  are 
placed  in  B  instead  of  the  iron  sulphide,  and  the  working 
is  the  same.  It  may  also  be  used  for  generating  hydrogen 
gas,  substituting  granulated  zinc  again  for  the  iron  sulphide 
or  the  marble,  but  in  this  case,  it  ^is  desirable  to  place 
around  the  tube  descending  from  A — that  is,  the  annular 
space  between  it  and  the  contracted  part  of  the  globe  B — 
a  disc  of  woven  asbestos  cloth  on  which  the  granulated 
zinc  may  rest,  to  obviate  its  passage  by  dropping  into  the 
part  C.  (See  also  Woulfe's  Bottle.) 

GAS  MANTLES  of  incandescent  character  are  prepared  from 
ramie  yarn,  artificial  silk,  and  other  materials,  by  impregna- 
tion with  mixtures  of  thoria  and  ceria — the  rare  earths 
which  are  found  in  monazite  sand  and  some  other  minerals. 


220       GAS  MANTLES— GAS  PRODUCERS 

GAS  MANTLES  (Continued)— 

After  impregnation  with  the  necessary  chemicals,  the 
mantles  are  lightly  coated  with  collodion  solution  to  give 
strength  to  the  texture. 

The  impregnation  is  ordinarily  effected  by  soaking  the 
mantles  in  a  solution  of  thorium  and  cerium  nitrates  in  the 
proportion  of  99  to  I,  other  substances  being  sometimes 
introduced  for  specific  reasons,  after  which,  and  before 
coating  with  collodion,  they  are  dried  and  ignited  to  burn 
off  the  fibre  and  cause  the  deposition  of  the  oxides  (thoria 
and  ceria)  from  the  nitrates  on  the  ash  skeletons  of  the 
mantles.  The  gas  mantle  at  its  lowest  efficiency  renders 
it  possible  to  obtain  fifteen  times  the  light  obtainable  from 
any  quantity  of  gas  stripped  of  its  cyclic  hydrocarbons. 

The  British  output  for  the  year  ended  October  30,  1920, 
was  82,322,000. 

GAS  PEODUCEES — There  are  several  forms  of  industrial  gas 
producers  (see  Producer  Gas),  but  in  that  form  known  as  the 
suction  gas  plant,  anthracite  is  the  fuel  that  is  used  and  this 
is  placed  in  a  cylindrical  furnace  (producer),  air  and  steam 
being  admitted  below  the  burning  fuel.  The  atmospheric 
oxygen  first  combines  with  the  burning  carbon  to  form 
carbon  dioxide,  and  this,  in  passing  through  the  red-hot 
mass,  is  converted  into  carbon  monoxide.  The  steam  is 
also  decomposed  to  some  extent,  forming  more  carbon 
monoxide  and  hydrogen  gas,  both  of  which  are  combustible, 
and  together  with  the  residual  nitrogen  of  the  air,  constitute 
the  so-called  "  water  gas,"  having  a  high  calorific  value. 
This  is  washed  and  cooled  in  a  scrubber  before  being 
sucked  in  by  the  piston  of  the  engine. 

Coke  and  peat  can  be  employed  in  the  place  of  an- 
thracite. 

Suction  gas  made  as  described  has  an  approximate 
composition  as  follows,  and  a  calorific  value  of  about 
140  B.T.U.  per  cubic  foot  : 

Carbon  monoxide  -.-%.  ...  1 8*6  per  cent. 

Hydrogen          ...  •».  •••  i?'6 

Methane            ...  ...  ...  1*6 

Carbon  dioxide  ...  ...  7*2 

Nitrogen           ...  ...  ...  54-4 

Oxygen              ...  ...  ...  0-6 

lOO'O 


GASOLINE— GASTRIC  JUICE  221 

GASOLINE  (Petrol,  Motor  Spirit) — Used  also  as  a  solvent, 
cleansing  agent,  in  paint-mixing,  and  making  rubber 
cements  ;  consisting  of  petroleum  distillate  fractions  boiling 
at  from  38°  to  100°  C.  (See  Petroleum.) 

GASSING  from  chlorine  in  chemical  works  is  not  infrequent, 
and  is  generally  caused  by  the  workmen  entering  the 
chambers  wherein  lime  has  been  chlorinated  in  course  of 
the  manufacture  of  bleaching-powder,  before  the  chlorine 
gas  has  been  exhausted,  and  at  other  times  owing  to 
accidental  leakages.  It  is  usual  for  the  workmen  to  hold 
rags  or  a  cloth  wetted  with  water  or  dilute  sodium  car- 
bonate in  their  mouths  to  prevent  injury. 

In  the  recent  war,  gassing  attacks  by  means  of  a  chlorine 
cloud  produced  by  the  use  of  liquefied  chlorine  were  made, 
and  various  other  substances  were  used,  including  cyanogen 
chloride  (CNC1)  (a  colourless,  poisonous  liquid,  which  boils 
at  13°  C.),  chlorinated  picric  acid  and  phosgene  (carbonyl 
chloride,  COC12)  (which  liquefies  below  +8°  C.,  and  yields 
a  gas  of  very  suffocating  odour),  xylyl  bromide  and  benzyl 
bromide  (with  which  "  tear  "  shells  were  at  first  filled),  and 
later,  chloromethyl  and  trichloromethyl  chloroformates — 
highly  poisonous  bodies. 

The  so-called  "  mustard  gas"  was  produced  by  the  use 
of  the  oily,  liquid,  dichlorethyl  sulphide  (CH2C1,CH2)2S 
(prepared  from  ethylene  by  the  action  of  sulphur  mono- 
chloride),  which,  although  it  does  not  produce  any  immediate 
effect  on  the  eyes,  brings  about  most  severe  inflammation 
and  intractable  blisters  later,  acute  pneumonia,  and  other 
serious  results,  due  to  its  hydrolysis  within  the  eye,  leading 
to  the  formation  of  hydrochloric  acid  in  the  live  cells. 

A  number  of  other  chemical  compounds,  including 
sulphur  trioxide,  were  also  employed. 

Suitable  chemical  reagents  for  neutralizing  these  various 
poisons  were  provided  as  far  as  possible,  being  used  in 
respirators. 

A  solution  containing  sodium  sulphide  and  soap,  used  in 
the  form  of  a  fine  spray,  has  been  found  very  effective  in 
purifying  the  air  from  certain  toxic  gases,  including  chloro- 
picrin,  chlorine,  phosgene,  methylchloroformates,  acrolein, 
bromoacetone,  cyanogen  chloride,  and  benzyl  iodide, 
bromide,  and  chloride. 

GASTRIC  JUICE  contains  in  1,000  parts  about  994  to  995  parts 
of  water,  5  per  cent,  of  various  saline  substances  (particu- 
larly sodium  chloride),  3  per  cent,  of  pepsin,  and  a  very 
small  quantity  of  free  acid,  including  hydrochloric  acid.  It 
has  the  power  of  dissolving  albuminous  substances  taken 


222  GASTRIC  JUICE—GEMS 

GASTRIC  JUICE  (Continued)— 

as  food,  thus  producing  peptones,  so  that  the  food  is  made 
assimilable. 

GAULTHERIA  OIL  (Oil  of  Wintergreen)— A  colourless  or 
slightly  red  essential  oil  of  sp.  gr.  1*175  to  1*185,  rotation 
-0-25°  to  -  i°,  and  boiling-point  about  218°  C,  obtained 
from  the  Gaultheria  procmnbens,  or  Canada  tea,  which  grows 
freely  in  New  Jersey.  It  exists  in  all  parts  of  the  plant, 
has  a  pleasant  odour,  and  contains  a  substance  in  the  nature 
of  a  methyl  combination  with  salicylic  acid  (C7H6O3),  from 
which  that  acid  can  be  prepared,  although  it  is  also  pro- 
duced synthetically.  It  is  soluble  in  alcohol,  ether,  chloro- 
form, and  carbon  disulphide,  and  is  used  in  perfumery, 
confectionery,  and  for  flavouring,  as  also  in  medicine. 

GEDDA — The  name  of  certain  East  Indian  waxes,  stated  to  con- 
tain 48  per  cent,  ceryl  alcohol  associated  with  fatty  acids,  etc. 

GEL— See  Colloid. 

GELATIN — An  albuminous  substance  forming  an  important 
constituent  of  many  animal  tissues,  including  cartilages, 
bones,  and  horn.  Commercially,  it  may  be  prepared  from 
bones  by  digesting  them  in  water  acidified  with  hydro- 
chloric acid,  which  assists  in  the  separation  of  the  gela- 
tinous parts  from  the  calcareous  parts.  In  the  dry  state 
it  is  almost  colourless  or  has  a  slightly  yellowish  tint.  It 
swells  when  placed  in  water  and  becomes  translucent,  but 
does  not  dissolve  to  any  great  extent,  although  it  passes 
into  solution  upon  heating.  Gelatin  as  prepared  from 
various  sources  differs  slightly  in  composition,  but  contains 
approximately  50  per  cent,  of  carbon,  6-5  to  7  per  cent, 
hydrogen,  and  from  17-5  to  i84per  cent,  nitrogen. 

Gelatin  is  largely  employed  in  the  preparation  of  jellies, 
foodstuffs,  confectionery,  adhesives,  medicinal  capsules,  and 
for  other  purposes. 

A  solution  of  even  i  per  cent,  gelatinizes  on  cooling. 
When  dried,  it  is  insoluble  in  alcohol  and  ether.  (See 
Albumin,  Isinglass,  Proteins,  Size,  and  Glue.) 

GELSEMININA  (Gelsemine)  (C22H26N2O3)— A  yellowish-white, 
crystalline  alkaloid,  of  melting-point  172°  C.  soluble  in 
alcohol  and  ether,  which  forms  salts,  and  has  mydriatic 
properties.  It  is  extracted  from  the  dried  rhizome  and 
roots  of  yellow  jasmine  (Gelsemium  nitidum,  etc.),  and  is 
imported  from  the  United  States. 

GEMS — Precious  stones,  such  as  the  diamond,  ruby,  topaz,  and 
emerald.  Imitations  of  them  consist  of  glasses,  but  the 


GEMS—GERMA  NI UM  223 

GEMS  (Continued)— 

ruby  and  the  sapphire  are  now  produced  commercially  by 
the  fusion  of  pure  alumina,  and  are  identical  in  all  respects 
with  the  natural  gems.  (See  Aluminium.) 

The  colour  of  the  ruby  is  due  to  a  small  content  of 
chromium,  as  also  probably  that  of  the  sapphire ;  the 
emerald  and  aquamarine  owe  their  green  tint  to  the  presence 
of  ferrous  iron,  and  are  varieties  of  beryls ;  the  amethyst 
and  the  garnet  also  owe  their  colours  to  ferric  iron  or 
manganese,  or  both. 

The  individual  gems  are  further  referred  to  under  their 
separate  names. 

GENTIAN  is  the  dried  root  of  the  Gentiana  lutea  which  grows 
abundantly  in  Switzerland,  the  Tyrol,  and  the  Auvergne. 
An  aqueous  infusion  is  used  as  a  bitter  tonic  in  medicine, 
a  substance  named  gentianic  acid  being  considered  the 
chief  active  principle.  The  root  contains  a  yellow  colour- 
ing matter. 

GERANIAL— See  Citral. 

GERANIOL  (C10H18O)  is  contained  in  a  number  of  essential 
oils,  and  is  the  chief  constituent  of  Indian  geranium  oil, 
which  is  used  as  a  substitute  for  otto  of  roses.  It  boils 
at  230°  C.,  has  a  sp.  gr.  of  0-88,  and  is  stereoisomeric 
with  terpineol.  (See  Citral.) 

GERANIUM  OIL  (Rose)— Distilled  from  the  herbs  Pelargonium 
radula,  P.  capitatum,  and  P.  odoratissimum  in  Algeria  and 
other  parts  of  Africa,  is  of  pale  yellow  or  greenish  colour, 
having  geraniol  as  its  chief  constituent.  It  is  soluble  in 
alcohol  and  ether,  has  a  sp.  gr.  of  0*886  to  0-898,  and 
rotation  of  -7°  to  12°.  It  is  used  in  perfumery.  (See 
Geraniol.) 

The  Turkish  Oil  (Palmarosa  Oil),  which  comes  really 
from  the  East  Indies,  has  a  sp.  gr.  of  0-890  to  0-900,  and 
is  distilled  from  the  grass  of  a  species  of  Andropogon.  It  is 
very  similar  to  the  "  rose "  oil,  and  used  for  the  same 
purposes. 

Japanese  oils,  obtained  respectively  from  Pelargonium 
graveolens,  P.  radula,  and  P.  denticulatum,  grown  near  Tokyo, 
and  recently  examined,  showed  sp.  grs.  of  0-9178,  0-9234, 
and  0-8860,  and  total  geraniol  content  as  follows:  23-1  per 
cent.,  26-3  per  cent.,  and  63-5  per  cent.,  the  P.  denticulatum 
variety  being,  therefore,  the  most  valuable  for  perfumery. 

GERMANIUM  (Ge) — Atomic  weight,  72-5 ;  sp.  gr.,  5-46 ; 
melting-point,  about  900°  C.  A  rare  element  (found  in  the 


224  GERM  A  NIUM—GLA  SS 

GERMANIUM  (Continued)— 

minerals  argyrodite  and  canfieldite),  of  which  little  is  known, 
and  described  as  both  metallic  and  non-metallic — that  is, 
on  the  borderland.  It  is  of  a  crystalline  character,  and  is 
said  to  combine  with  the  alkaline  hydrates  forming  com- 
pounds corresponding  to  silicates.  There  is  an  oxide  (GeO), 
a  chloride  (GeCl2),  and  a  sulphide  (GeS). 

GERMAN  SILVER— See  Alloys. 

GERMICIDES — Chemical  preparations  that  kill  bacteria  and 
other  germs. 

GERMS— See  Bacteria  and  Microbes. 

GHEE — A  clarified  butter  made  from  buffalo  milk,  with  or 
without  added  cow's  milk,  from  which  moisture,  casein,  and 
other  constituents,  except  the  fat,  have  been  removed.  It 
is  prepared  in  Somaliland  and  India,  and  is  used  both  in 
cooking  and  as  a  food.  It  has  a  melting-point  varying  from 
34°  to  37*3°  C.,  a  saponification  value  of  from  227  to  238, 
and  an  average  Reichert-Wollny  value  of  34*5. 

GIN  is  spirit  distilled  from  fermented  wort  of  malted  barley,  and 
flavoured  with  juniper  berries  by  distillation  or  otherwise. 

GINGER  is  the  root  of  Zingiber  officinale,  which  grows  in  India 
and  other  tropical  places,  and  contains  a  number  of  chemical 
substances,  including  about  1*5  per  cent,  of  a  volatile  oil, 
"  gingerol,"  which  is  said  to  contain  some  terpenes  and  a 
mixture  of  two  homologous  bodies,  C17H2gO4  and  C18H28O4, 
also  another  substance  called  zingerone  (CuH^Og).  Apart 
from  its  use  as  a  spice,  it  is  used  as  an  aromatic  addition  to 
griping  medicines. 

"  Gingerol "  is  used  in  flavouring  and  in  compounding 
liqueurs. 

GINGER  OIL — Obtained  by  distillation  from  the  rhizome  of 
Zingiber  officinale,  is  a  yellowish,  aromatic  oil  of  burning 
taste,  soluble  in  alcohol  and  ether,  with  a  sp.  gr.  of  about 
of88,  and  is  used  for  flavouring  purposes. 

GINGER-GRASS  OIL  is  distilled  from  the  grass  of  a  species  of 
Andropogon,  somewhat  resembling  geranium  oil  in  character, 
and  is  used  in  perfumery. 

GLACIAL  ACETIC  ACID — See  Acetic  Acid. 

GLASS — A  fused  mixture  of  silicates  of  potassium  or  sodium 
with  one  or  more  other  silicates  which  are  insoluble  in  water, 
such  as  silicate  of  calcium,  magnesium,  etc.,  the  silicates  of 
the  alkalies  alone  being  soluble  in  water.  In  practice, 


GLASS  225 

GLASS  (Continued)— 

ground  quartz  or  flint  or  clean  sand,  mixed  with  potassium 
or  sodium  carbonate  and  the  other  ingredients,  are  fritted 
together  in  an  oven  or  furnace,  by  which  means  the  silica 
constituting  the  quartz  or  sand  enters  into  combination  with 
the  bases,  thus  forming  glass. 

It  is  of  importance  that  the  sand  should  be  of  high  purity 
(98  to  100  per  cent.  SiO2)  and  free  from  iron  oxides,  or 
nearly  so. 

There  are  many  and  very  great  varieties  of  glass,  differ- 
ing from  each  other  in  their  respective  compositions, 
qualities,  and  uses.  When  the  mixture  used  (as  for  plate- 
glass-making)  consists  only  of  sodium  carbonate,  calcium 
carbonate,  and  sand,  the  two  carbonates  first  of  all  fuse 
together,  and  then  at  a  higher  temperature  they  are  decom- 
posed by  the  silica  (of  the  sand),  the  two  bases  combining 
therewith,  whilst  carbon  dioxide  is  evolved. 

Window  Glass  is  made  by  fusion  from  a  mixture  of  sand, 
sodium  carbonate  or  sodium  sulphate,  and  limestone  in  fire- 
clay pots. 

Bohemian  Glass  is  made  from  pure  potassium  carbonate 
and  powdered  quartz,  and  is  not  so  fusible  as  window  glass. 

Flint  and  Lead  Glass  are  made  from  ground  flint,  lead 
oxide,  and  potassium  carbonate,  with  or  without  some 
added  nitre,  and  is  very  fusible  ;  the  ordinary  household 
glass  articles  being  made  from  this  quality. 

Bottle  Glass  of  green  colour  is  made  of  silicates  of  sodium, 
calcium,  and  aluminium,  the  colouring  being  supplied  by 
oxide  of  iron.  To  impart  other  colours,  other  metallic  oxides 
are  used,  that  of  manganese  giving  a  purple  tint,  cobalt 
oxide  a  blue  colour,  copper  oxide  a  ruby  red ;  glasses  free 
from  heavy  metals  are  coloured  yellow  by  sulphur;  to 
strongly  alkaline  glasses  selenium  gives  a  chestnut-brown 
colour ;  tellurium  can  be  used  to  give  a  purple-red  and  in 
some  other  cases  a  blue  colouration ;  chromium  oxide  gives 
greens  or  reds;  and  so  on. 

Arsenious  oxide  is  used  in  making  many  qualities  of  glass 
amongst  other  purposes  to  correct  the  green  tint  which 
traces  of  iron  would  otherwise  give  to  it,  by  oxidizing  it 
from  a  ferrous  state  into  a  ferric  state. 

For  chemical  apparatus,  a  soda-lime  glass  is  preferred  for 
the  most  part,  although  the  potash-lime  glass  is  superior 
when  the  articles  to  be  made  should  be  hard  or  difficult  to 

15 


226 


GLA  SS—GLA  SS-B  LO  WING 


GLASS  (Continued)— 

fuse   as,  for   instance,   glass   combustion   tubing   used   in 
making  organic  analyses. 

Up  to  the  time  of  the  recent  war,  Thuringia  and 
Bohemia  enjoyed  almost  a  monopoly  of  this  glass 
industry ;  but  as  a  result  of  investigations  conducted 
by  British  chemists  during  the  war,  working  formulae  or 
recipes  for  a  number  of  qualities  for  chemical  and  other 
scientific  purposes  have  been  successfully  introduced  to 
manufacturers  in  this  country  for  which  we  were  previously 
entirely  dependent  upon  those  and  German  supplies.  One 
of  the  best  of  these  is  a  zinc-aluminium-borosilicate  quality. 
The  analysis  of  a  Jena  glass  beaker  gave  the  following 
composition  :  SiO2,  64-66  per  cent. ;  A12O3,  674  per  cent. ; 
ZnO,  10-12  per  cent. ;  CaO,  0*08  per  cent. ;  MgO,  0-13  per 
cent. ;  Na2O,  7-21  per  cent. ;  B2O3,  11-14  per  cent. ;  Fe2O3, 
o'io  per  cent. ;  the  salient  components  being  the  A12O3, 
ZnO,  B2O3,  the  silica,  and  the  alkali. 

Some  published  analyses  of  glass  are  as  below  : 


Plate. 

Window. 

Lime 
Flint. 

Lead 
Flint. 

Bohemian. 

Per 

Per 

Per 

Per 

Per 

Cent. 

Cent. 

Cent. 

Cent. 

Cent. 

Si02          

71 

71 

74 

54 

71 

CaO           

J3 

II 

10 

PbO          



— 

35 



Na20         
K20           
Al2O3and  Fe2O3... 

H 
I  tO  2 

J5 

I  tO  2 

19 

II 

2-5 
12-5 

9 

The  tests  of  good  glasses  for  chemical  use  include  the 
action  of  boiling  water,  boiling  water  under  pressure 
(autoclave),  and  the  action  of  acids  and  alkalies. 

Fused  Silica  or  Quartz  Glass  of  opaque  and  transparent 
characters  is  now  largely  used  in  the  construction  of  chemical 
apparatus,  as  it  only  melts  at  about  the  same  temperature 
as  platinum,  and  is  very  resistant  to  the  action  of  chemicals. 
Moreover,  it  is  not  liable  to  breakage  by  sudden  changes  of 
temperature.  (See  also  Porcelain.) 

GLASS-BLOWING — An  art  that  can  only  be  acquired  by 
practice.  Suppose  it  is  desired  to  make  a  sealed  tube  with 
a  bulb  at  one  end,  a  piece  of  glass  tube  of  the  desired  size 


GLASS-BLOWING  227 

GLASS-BLOWING  (Continued)— 

and  length — say  ~  inch  diameter  and  4  or  5  inches  in 
length — is  taken,  and  one  end  placed  in  a  Bunsen  or  blow- 
pipe flame  until  the  glass  softens  sufficiently  to  mass 
together,  close  up,  and  become  solid  to  the  extent  of  about 
i  inch.  (See  Blow-pipe.)  Whilst  still  red-hot  and  soft,  the 
mouth  should  be  applied  to  the  open  end,  turning  the  tube 
round  in  the  fingers,  and  meantime  blowing  with  enough 
pressure  to  swell  out  the  molten  glass.  It  may  be  neces- 
sary, and  often  is  so,  to  reheat  the  blown-out  part  and  repeat 
the  blowing  until  a  bulb  of  the  right  size  and  shape  is 
obtained. 

Bulb-tubes  thus  prepared  are  useful  for  observing  the 
behaviour  of  solid  chemical  substances  placed  in  them  for 
that  purpose  when  heat  is  applied.  The  conveyance  to  the 
bulb-tube  of  the  substance  to  be  examined  can  be  easily 
effected  by  the  use  of  a  sharply  channelled  slip  of  paper. 

Iodine  will  be  seen  to  volatilize,  and  give  off  fumes  of  its 
own  colour,  and  to  recondense  to  the  solid  state  in  the 
upper  (cooler)  part  of  the  tube. 

Sulphur  can  be  seen  to  melt  and  pass  through  the  stages 
described  under  that  heading,  including  sublimation  and 
recondensation. 

Mercury  can  be  sublimed  and  seen  to  condense  on  the 
upper  cool  part  of  the  tube  ;  so  also  ammonium  chloride. 

Lead  filings  can  be  melted  in  the  bulb. 

White  lead  is  decomposed,  carbon  dioxide  being  given 
off  as  gas,  and  yellow  litharge  being  left  behind  in  the  tube. 

Glass  T-pieces  can  be  made  with  a  little  practice,  and 
are  often  wanted  in  the  laboratory.  Take  a  piece  of  glass 
tube  of  the  desired  length,  and  plug  one  end  with  a  small 
boring  of  cork  ;  then  hold  it  in  the  flame  of  a  blow-pipe  so 
that  a  fine  tongue  of  flame  impinges  upon  and  heats  the 
tube  in  one  spot  only,  near  the  middle ;  and  when  it  is 
observed  to  be  red-hot,  remove  the  tube  from  the  flame 
and  place  the  open  end  quickly  in  the  mouth.  Upon 
blowing,  the  molten  part  will  become  distended  into  the 
shape  of  a  swelling  or  balloon,  so  thin  that  it  can  easily  be 
broken,  thus  leaving  a  hole  in  the  tube,  the  edges  of  which 
can  be  rounded  off  with  a  file.  Next,  take  another  piece 
of  glass  tube  and  blow  a  bulb  at  one  end  as  previously 
described,  taking  care,  however,  in  this  case  to  blow  the 
bulb  as  large,  and  therefore  as  thin,  as  possible.  This  bulb 
is  then  to  be  broken  and  the  edges  rounded  off  as  in  the 
other  case  with  a  file,  when  it  remains  to  join  the  two 
pieces  together.  We  have  then  the  one  tube  with  a  hole 


228  GLASS  BLOWING— GLOBULINS 

GLASS-BLOWING  (Continued)— 

in  its  centre,  and  the  other  tube  with  one  end  provided  with 
a  sort  of  lip  roughly  fitting  the  hole  as  to  size.  The  flame 
of  the  blow-pipe  should  now  be  applied  to  both  these  parts, 
and  when  sufficiently  softened  by  the  heat  they  can  be 
joined  together  (welded)  in  the  flame. 

GLASS  TUBES  are  of  various  diameters,  and  can  be  connected 
together  when  desired  by  rubber  tubing.  The  ordinary 
size  is  about  5  millimetres  outside  diameter.  They  can 
be  bent  to  any  desired  shape  by  heating  (meantime  turning 
them  round),  until  softened,  in  the  flame  of  a  fish-tail  gas 
burner,  and  then  applying  pressure  by  the  hands  until  the 
desired  bend  or  angle  is  reached.  A  glass  tube  can  be 
drawn  out  to  a  smaller  dimension  or  to  a  fine  point  when 
heated,  as,  for  example,  when  it  is  desired  to  make  the 
longer  pointed  tube  for  use  in  a  wash-bottle.  When  the  tube 
so  drawn  out  has  cooled,  it  is  cut  at  the  drawn-out  part. 
During  this  heating,  the  tube  becomes  covered  with 
deposited  soot  (due  to  the  imperfect  combustion  of  the 
carbon  constituents  of  the  gas),  and  it  is  best  to  leave  this 
on  the  glass  until  it  is  cold,  as  by  so  doing  the  cooling 
(annealing)  is  prolonged  and  there  is  consequently  less 
liability  to  fracture. 

To  cut  a  glass  tube,  place  flat  on  the  bench,  and  then 
with  the  edge  of  a  triangular  file  make  a  scratch  where  it  is 
to  be  cut.  Upon  grasping  the  tube  firmly  in  both  hands 
and  application  of  gentle  pressure,  it  should  break  evenly 
across.  When  the  tube  is  thick  or  the  diameter  greater, 
several  file  markings  should  be  made  in  the  same  circum- 
ferential ring,  or  the  filings  should  be  made  deeper. 

The  rough  edges  of  glass  tubes  can  be  ground  off  with 
a  flat  file  or  rounded  off  evenly  by  softening  in  the  edge  of 
a  Bunsen  flame. 

GLAUBERITE — A  crystalline  native  double  sulphate  of  sodium 
and  calcium  (Na2Ca(SO4)2),  occurring  in  New  Castile, 
Arizona,  New  Mexico,  Bavaria,  at  Vic  (France),  and  at 
Tarapaca  in  Peru. 

GLAUBER'S  SALTS— Sodium  sulphate  (Na2SO4,ioH2O). 

GLAZES — Fusible  mixtures  of  felspar  and  other  substances 
used  in  the  ceramic  industries.  (See  Porcelain  and 
Refractories.) 

GLOBULINS — A  class  of  proteins  insoluble  in  water  but  soluble 
in  a  dilute  solution  of  salt,  including  globulin  from  the 
crystalline  lens  of  the  eye,  and  fibrin  of  blood.  (See 
Proteins.) 


GL  UCIN  UM—GL  UCOSE  229 

GLUCINUM  (Gl)  or  BERYLLIUM — atomic  weight,  o/i ;  sp.  gr., 
about  i'75  to  i'85;  melting-point,  1,280°  C. — is  found  in 
nature  in  a  number  of  minerals,  including  the  beryl  (a  double 
silicate  of  glucinum  and  aluminium).  It  is  a  steel-grey, 
fairly  malleable  metal  resembling  magnesium,  which,  when 
strongly  heated,  is  converted  into  oxide  (G1O),  and  when 
in  a  pulverulent  form  takes  fire.  A  white  crystalline 
chloride  (G1C12)  is  known,  and  the  metal  itself  is  obtained 
by  heating  metallic  sodium  in  the  vapour  of  this  chloride, 
which  is  volatile.  The  metal  can  also  be  obtained  by  the 
electrolysis  of  the  double  fluoride  of  glucinum  and  potas- 
sium. It  is  soluble  in  dilute  acids,  and  forms  an  alloy 
with  copper.  Many  of  its  compounds,  including  fluorides 
(GIF  and  G1F2),  chloride  (G1C12),  bromide,  iodide,  sulphide, 
carbide,  sulphates,  nitrate,  etc.,  in  general  characters  re- 
semble the  aluminium  compounds. 

GLUCOSE  (Dextrose) — There  are  a  number  of  sugar-like 
bodies  termed  glucoses,  of  which  the  best-known  member 
is  grape  sugar,  or  dextrose  (C6H12O6,H2O).  It  is  con- 
tained in  honey  and  in  most  sweet  fruits,  and  can  be 
prepared  from  sucrose  (cane  sugar)  or  starch  by  the 
action  of  dilute  acids  (hydrolysis).  Commercial  glucose  is 
chiefly  made  by  the  prolonged  action  of  dilute  sulphuric 
acid  upon  maize  or  other  starch,  and  is  stated  to  be  a 
mixture  of  real  glucose  with  varying  proportions  of 
dextrin  and  maltose.  The  sulphuric  acid  is  removed  by 
chemical  means  and  the  syrup  evaporated  in  vacuum  pans 
until  semi-solid,  after  which  it  can  be  run  into  moulds, 
constituting  when  cold,  a  hard  opaque  substance,  white  or 
slightly  yellow  in  colour,  used  extensively  in  the  confec- 
tionery, jam,  and  syrup  trades.  Glucose  in  the  nature  of 
imperfectly  converted  starch  and  containing  up  to  50  or 
more  per  cent,  of  inverted  products  other  than  glucose,  is 
made  largely  for  use  by  brewers  and  in  manufacturing  con- 
fectionery, wines,  etc. 

When  cane  sugar  is  hydrolyzed  by  acid  treatment  it  is 
converted  into  so-called  "  invert  sugar  " — that  is,  a  mixture 
of  glucose  with  fructose,  and  it  has  been  shown  that  these 
two  substances  and  mannose — another  variety  of  glucose 
obtained  from  mannitol — are  partially  and  mutually  trans- 
formable. Inverted  sugar  is  uncrystallizable. 

When  glucose  is  heated  to  150°  to  155°  C.  under  reduced 
pressure,  it  loses  water  and  is  converted  into  the  anhydride 
glucosane  (CgH^Og),  which  can  be  obtained  in  a  deli- 
quescent crystalline  form,  melting  at  108°  to  109°  C., 


23o  GL  UCOSE-GL  U  CO  SIDES 

GLUCOSE  (Continued)— 

and,    when    heated    with    water,    is    retransformed    into 
glucose. 

By  heating  cotton  cellulose  in  a  distilling  apparatus 
under  a  pressure  of  10  to  15  mm.  it  decomposes  at  210°  C., 
and  an  oil  equal  in  weight  to  45  per  cent,  of  the  cellulose, 
distils  over  and  subsequently  solidifies  with  a  composition 
represented  by  C6H10O5,  and  supposed  to  be  the  anhydride 
named  laevo-glucosan.  Quite  recently,  it  has  been  de- 
finitely proved  that  crystalline  glucose  (melting-point 
145°  F.)  can  be  obtained  from  normal  cotton  cellulose. 
(See  Dextrose  and  Invertase.) 

GLUCOSIDES — A  class  of  organic  compounds  found  present  in 
many  vegetable  tissues,  which  are  resolved  by  hydrolysis 
(as  effected  by  the  action  of  enzymes,  acids,  or  alkalies) 
into  a  sugar  (usually  glucose)  and  other  simpler  organic 
substances. 

Amygdalin  (C20H27NO11)is  a  white,  crystalline  glucoside 
found  present  in  the  bitter  almond,  and  is  decomposed  in  the 
presence  of  water  by  the  action  of  an  enzyme  (emulsin) 
contained  in  the  tissue  of  the  almond  as  follows : 

C20H27NOn  +  aH2O  =  C7H6O  (benzaldehyde)  + 
HCN  (hydrocyanic  acid)  +  2C6H12O6  (glucose). 

Other  glucosides  are — 

Arbutin  (C12H1gO7),  from  the  leaves  of  the  bear-berry, 
resolved  by  emulsin  into  glucose  and  hydroquinone. 

Phloridzin  (C21H24O10) — A  constituent  of  the  root  bark  of 
apple,  pear,  cherry,  and  plum  trees. 

Salicin  (C13H18O7) — Present  in  the  bark  of  the  willow  and 
in  poplar  buds. 

Coniferin  (C^H^Og^HaO) — Contained  in  the  cambium 
sap  of  various  fir-trees. 

Indican — From  which  indigo  is  made.     (See  Indigo.) 

Hederin  (C64H104O19) — From  ivy. 

Hesperidin  (C22H26O12) — A  constituent  of  unripe  oranges. 

^Esculin  (C15H16O9) — Contained  in  the  horse-chestnut 
bark. 

Digitonin,  Digitalin,  and  Tannin. 

Most  of  the  glucosides  are  hydrolyzed  by  emulsin  in 
particular,  but  are  accompanied  in  the  plant  tissues  contain- 
ing them,  by  an  enzyme  which  is  also  capable  of  effecting 
their  hydrolysis.  (See  Hydrolysis.) 


GLUE— GLYCERINE  231 

GLUE — A  gelatinous  body  made  from  the  parings  of  hides,  the 
pith  of  horns,  and  other  animal  offal,  by  boiling  them  with 
water.  The  liquid  thus  prepared,  is  afterwards  poured  into 
frames  or  moulds,  in  which  it  sets  to  a  solid  mass.  Fish 
glue  is  made  from  the  bony  structures  of  the  heads  of 
fishes.  It  is  largely  used  for  making  adhesives,  finishing 
textiles,  in  the  felt-hat  trade,  etc.  A  good  glue  should  not 
attract  moisture,  and  should  be  capable  of  absorbing  six  to 
seven  times  its  own  weight  of  water  without  liquefying. 
(See  Isinglass.) 

GLUE  (Liquid)  is  made  by  treating  ordinary  glue  with  acetic 
or  hydrochloric  acid,  wnen  it  loses  its  gelatinizing  property, 
but  retains  its  adhesiveness. 

GLUTEN  or  VEGETABLE  ALBUMEN— The  albuminoid  or 
protein  part  of  wheat  flour,  amounting  to  from  10  to  15  per 
cent,  in  the  best  qualities,  and  in  inferior  grades  to  from 
8  to  9  per  cent.  It  is  that  part  of  the  flour  which  when 
made  into  a  paste  and  washed  with  water  forms  the 
tenacious  part  as  distinct  from  that  portion  which  dis- 
solves in  the  water  and  the  starch  which  goes  into  suspen- 
sion in  the  water.  It  is  soluble  in  alkalies  and  in  strong 
acetic  acid. 

GLYCERIC  ACID  (C3H6O4)— A  thickish  liquid  resulting  from 
the  oxidation  of  glycerol  (glycerine)  by  nitric  acid :  it 
enters  into  combination  with  the  alkalies  and  other  bases, 
forming  salts  known  as  glycerates. 

GLYCEEIDES — Esters  of  glycerol  (glycerine)  as  contained  in 
fats  and  many  oils.  (See  Esters  and  Fats.) 

GLYCERINE  or  GLYCEROL  (C3H8O3)— A  syrupy,  colourless, 
and  odourless  liquid  of  a  somewhat  sweet  taste,  and  sp.  gr. 
1-27.  It  is  soluble  in  water  and  alcohol,  solidifies  to  a 
crystalline  condition  when  exposed  to  a  sufficiently  low 
temperature  (below  17°  C.),  and  boils  at  290°  C.  It  is 
chemically  described  as  a  trihydric  alcohol  (C3H5(OH)3) 
and  is  a  product  of  the  decomposition  (saponification)  of 
fats  and  many  oils,  being  practically  manufactured  on  a 
large  scale  from  the  spent  lyes  resulting  from  soap-making. 
The  alkali  used  for  soap-making  combines  with  the  fatty 
acids  to  make  soaps,  while  the  glycerine  passes  into  solution 
and  is  recovered  from  the  lyes. 

It  is  also  produced  by  distilling  fats  in  superheated  steam, 
by  which  process  they  are  also  hydrolyzed,  the  glycerine 
passing  over  with  the  steam,  leaving  the  fatty  acids  behind ; 
or  the  fats  can  be  hydrolyzed  by  heating  in  water  to  which 
a  small  quantity  of  sulphuric  acid  has  been  added,  and  with 


232  GLYCERINE— GLYCINE 

GLYCERINE  (Continued)— 

or  without  the  addition  of  other  catalytic  agents.  In  such 
case,  the  fatty  acids  rise  and  float  on  the  top  of  the  liquid 
which  contains  the  glycerine  and  from  which  it  can  be 
easily  recovered. 

Glycerine  has  been  obtained  to  some  considerable  extent 
in  Germany,  and  more  recently  in  the  United  States  of 
America,  from  molasses  and  sugar,  by  a  process  of  fermen- 
tation with  a  selected  yeast  (S.  ellipsoideus)  in  an  alkaline 
medium.  Commercial  sucrose,  dextrose,  laevulose,  or  invert 
sugar  can  be  fermented  with  yeast  in  the  presence  of 
one  or  more  inorganic  or  organic  substances  of  alkaline 
reaction,  such  as  disodium  phosphate,  sodium  or  ammonium 
carbonate,  or  sodium  bicarbonate,  with  or  without  catalysts 
such  as  manganese  or  iron  sulphate.  The  fermentation  is 
preferably  conducted  in  the  presence  of  sodium  sulphite 
together  with  a  small  quantity  of  a  hydrosulphite  or  sulph- 
oxylate,  and  the  yeast  can  be  regenerated  by  a  purifying 
fermentation  in  presence  of  dilute  acid  and  used  over  again 
together  with  a  surplus  yield,  which  can  be  employed  for 
baking  or  fodder.  In  this  way  the  yield  of  glycerine 
amounts  to  from  23  to  367  per  cent,  of  the  sugar. 

Glycerine  is  largely  used  in  the  manufacture  of  nitro- 
glycerine and  other  explosives,  in  the  preparation  of 
perfumes,  cosmetics,  printing-ink  rollers,  liqueurs,  fruit 
preservatives,  blacking,  and  (when  mixed  with  5  or  6 
parts  water)  as  a  lotion  for  chapped  and  sunburnt  skins. 
It  can  be  distilled  in  vacuo  or  in  the  presence  of  steam 
without  decomposition,  but  it  undergoes  decomposition 
when  heated  in  the  air. 

Glycerine  never  freezes  at  atmospheric  temperatures, 
and  is  sometimes  used,  therefore,  as  a  lubricant  for  delicate 
machinery. 

GLYCEROPHOSPHORIC  ACID  (C3H9PO6)  (sp.  gr.  1-125)— A 
cleavage  liquid  product  from  complicated  substances  con- 
tained in  the  yolks  of  egg  and  brain  matter.  It  is  soluble 
in  water  and  alcohol ;  forms  a  characteristic  compound  with 
lead  (C3H7PbPO6)  and  is  an  ester  of  glycerol  (glycerine). 

GLYCINE  (Glycocoll)  or  AMINO-ACETIC  ACID  (C2H5NO2)— 
A  white,  crystalline  substance,  which  melts  at  about 
234°  C.,  soluble  in  water  and  of  sweet  taste,  which  behaves 
both  like  a  base  and  an  acid  forming  salts — that  is  to  say, 
with  both  acids  and  bases.  It  can  be  prepared  chemi- 
cally by  several  methods,  but  it  is  especially  interesting 
considered  as  a  derivative  of  wool  and  silk  and  as  a 


GLYCINE—GOLD  233 

GLYCINE  (Continued)— 

product  of  the  hydrolysis  of  certain  albuminous  bodies, 
because  it  is  believed  that  a  mixture  of  amino- acids, 
together  with  sufficient  amounts  of  fat,  starch,  sugar,  and 
the  necessary  saline  bodies,  will  maintain  life  without  the 
use  of  proteins.  (See  Amino-acids,  Foods,  and  Vitamines.) 

GLYCOGEN  (CgH10O5) — An  amylaceous  or  dextrin-like  sub- 
stance contained  in  the  liver  and  placenta  of  animals.  It 
combines  with  water  to  form  a  gummy  body,  and  its 
aqueous  solution  rotates  polarized  light  to  the  right  four 
times  as  much  as  dextrose.  When  boiled  with  dilute  acids 
it  is  changed  into  maltose. 

GLYCOLLIC  ACID  (C2H4O3)  occurs  naturally  in  the  juice  of 
the  sugar-cane,  in  unripe  grapes  and  the  leaves  of  the  wild 
vine,  and  may  be  prepared  in  a  number  of  ways,  including 
the  oxidation  of  glycol.  It  is  a  colourless,  crystalline, 
deliquescent  substance,  which  melts  at  78°  C.,  and  is  soluble 
in  water  and  alcohol.  By  the  action  of  nitric  acid  it  is 
converted  into  oxalic  acid. 

GLYCOLS— See  Alcohols. 

GLYCURONIC  ACID  (C6H10O7)— A  product  obtained  from 
saccharic  acid  by  reduction  with  sodium  amalgam. 

GNEISS — A  more  or  less  laminated  mineral  of  granite 
character  containing  mica. 

GOA  POWDER— See  Chrysophanic  Acid. 

GOLD  (Aurum,  Au) — Atomic  weight,  197;  sp.  gr.,  19*3;  melt- 
ing-point, 1,063°  C.  Gold  is  widely  distributed  in  nature 
and  is  found  for  the  most  part  in  the  free  or  metallic 
condition  in  quartz  veins  and  alluvial  deposits  resulting 
from  the  gradual  disintegration  of  gold-bearing  (older 
sedimentary  or  plutonic)  rocks.  It  is  extracted  from 
quartz  by  crushing  and  amalgamation  with  mercury,  and 
from  alluvial  deposits  by  mechanical  washing  with  water, 
the  water  carrying  away  the  lighter  associated  substances 
and  leaving  the  heavier  gold  behind.  When  the  amalgam 
process  is  used,  the  gold  is  obtained  from  the  amalgam 
by  distilling  off  the  mercury,  the  gold  being  left  behind. 

There  are  other  methods  of  extracting  gold  from  its  ores, 
in  one  of  which  potassium  cyanide  (KCN)  is.  used  on  a 
very  large  scale.  The  crushed  ore  containing  gold  in  a 
finely  divided  condition  is  treated  with  a  solution  of  the 
potassium  cyanide  containing  from  J  to  i  per  cent,  while 


234  GOLD 

GOLD  (Continued)— 

freely  exposed  to  the  air.  This  dissolves  the  gold,  which 
is  afterwards  precipitated  from  the  solution  by  means  of 
metallic  zinc  or  by  electrolytic  action,  using  lead-foil  cath- 
odes for  that  purpose,  and  subsequently  fused. 

When  zinc  is  used,  the  solution  containing  the  gold  in 
the  form  of  a  double  cyanide  of  potassium  and  gold  under- 
goes chemical  change  as  follows  : 

2KAu(CN)2  +  Zn  =  K2Zn(CN)4  +  2Au ; 

that  is  to  say,  the  zinc  replaces  the  gold  in  the  double 
cyanide  and  the  gold  is  set  free. 

Gold  is  comparatively  soft,  yellow  in  colour,  and  the 
most  malleable  and  ductile  of  all  metals,  admitting  of 
being  .beaten  into  an  extremely  fine  form  of  leaf,  which  is 
used  for  gilding  and  other  purposes.  It  can  be  beaten  out 
into  sheets  so  thin  that  280,000  are  required  to  make  one 
inch  in  thickness.  Gold  is  not  attacked  by  acids,  with  the 
exception  of  aqua  regia  (nitrohydrochloric  acid),  in  which 
it  dissolves,  forming  auric  chloride  (AuCl3). 

Alloyed  with  copper  and  silver,  it  is  largely  used  for 
coinage  and  other  purposes.  Pure  gold  is  described  as 
24-carat  gold,  whilst  i8-carat  gold  consists  really  of  18 
parts  of  gold  and  6  parts  copper  or  silver.  In  this  country 
the  legal  standard  is  22-carat  gold,  and  English  gold  coin 
consists  of  ii  parts  gold  and  i  part  copper.  It  is  also  used 
in  dentistry  and  the  preparation  of  amalgams. 

Electro-gilding  of  other  metals,  is  carried  out  by  using  a 
solution  of  the  double  cyanide  of  gold  and  potassium 
(AuK(CN)2).  (See  Electricity.) 

Aurous  oxide  or  gold  suboxide  has  the  formula  Au2O, 
and  is  insoluble  in  water. 

Auric  or  gold  oxide  (Au2O3)  is  a  brown  powder,  which 
is  also  insoluble  in  water,  combines  with  ammonia  to  form 
a  substance  of  indefinite  composition  named  fulminating 
gold,  which  explodes  easily  when  heated  to  100°  C.  or 
struck  with  a  hammer. 

There  are  two  chlorides,  AuCl  and  AuCl3,  both  of  which 
are  soluble  in  water,  the  latter  being  the  more  important. 
It  is  formed  when  gold  is  dissolved  in  aqua  regia,  and 
can  be  obtained  in  yellowish-red  crystals  having  the  com- 
position AuCl3,2H2O,  which  lose  their  water  of  crystalliza- 
tion upon  heating,  and  change  to  a  brown  mass. 

The  trichloride  is  used  in  photography  and  gold- 
plating. 

When  a  neutral  solution  is,  added  to  a  dilute  solution  of 


GOLD—GRA  VITA  TION  235 

GOLD  (Continued}— 

a  mixture  of  the  two  chlorides  of  tin,  a  purple  colour  is 
produced  known  as  "  purple  of  cassius,"  which  is  used  in 
the  manufacture  of  ruby  glass  and  colouring  enamels,  etc. 

The  double  chloride,  gold-potassium  chloride  (AuCl3. 
KC1,2H2O),  is  a  yellow,  crystalline  salt  used  in  painting 
porcelain  and  glass. 

GOLDBEATEKS'  SKIN— Peritoneal  membrane  from  the  intes- 
tinal tube  of  the  ox  and  other  animals,  soaked  in  a  weak 
solution  of  potash;  then,  after  washing,  stretched  and  beaten 
out  with  a  hammer,  and  finally  treated  so  that  it  cannot 
undergo  putrefaction. 

GONIOMETER — An  instrument  for  measuring  the  angles  of 
crystals. 

GOOCH  CRUCIBLE— See  Crucibles. 

GOULARD  WATER— A  very  dilute  solution  of  lead  acetate 
used  for  bathing  weak  eyes,  etc. 

GRAINS  OF  PARADISE  (Melleguetta  Pepper)— The  fruit  of 
certain  zingiberaceous  plants  (Amomum  melleguetta)  grown 
in  Ceylon  and  on  the  western  coast  of  Africa ;  used  as  a 
condiment  and  in  medicine. 

GRANITE — Rocks  of  felspar  and  mica  in  a  mass  of  quartz, 
often  associated  with  other  minerals. 

GRAPE  SUGAR  or  GLUCOSE— See  Dextrose,  Glucose,  Sugars, 
and  Carbohydrates. 

GRAPHITE— See  Carbon. 

GRAVITATION — The  science  of  gravitation  is  said  to  have 
changed  physical  astronomy  into  a  mechanism  of  the 
heavens. 

Kepler  discovered  the  mathematical  laws  by  which  the 
planets  are  balanced  in  space,  and  according  to  the  law  of 
gravitation  weight  is  determined,  the  weight  of  any  sub- 
stance being  the  measure  of  its  attraction  by  the  earth. 
In  other  words,  weight  is  defined  as  an  acquired  property 
of  matter  produced  by  an  attractive  force  emanating  from 
the  centre  of  the  earth.  Weight  diminishes  with  distance 
from  the  earth,  so  that  a  mass  of  lead  weighing  1,000  Ib. 
at  sea-level  weighs  2  Ib.  less  at  a  height  of  four  miles. 

The  intensity  of  gravitation  is  inversely  as  the  square  of 
the  distance  of  the  gravitating  body. 


236  GRA  VITA  TION—G  UA I A  C-  WOOD  OIL 

GRAVITATION  (Continued)— 

Some  forty-two  theories  have  been  propounded  to  account 
for  gravitation,  and  among  these,  adhesion  (as  between  two 
clean  plates  of  metal),  cohesion,  and  capillary  attraction, 
together  with  gravitation,  have  all  been  viewed  in  common 
as  manifestations  of  magnetic  force ;  but  while  no  fact  has 
at  present  been  found  which  is  necessary  for  the  substan- 
tiation of  any  of  them,  it  is  thought  that  the  further  study 
of  atoms  and  their  structure  will  throw  light  upon  the  true 
nature  of  gravitation. 

The  fall  of  an  apple  from  tree  to  earth,  the  tidal  waves, 
the  courses  of  the  planets  round  the  sun,  and  the  move- 
ments of  all  the  heavenly  bodies,  are  attributed  to 
gravitation. 

GRAVITIES— See  Densities,  Specific  Gravity,  and  Hydro- 
meter. 

GREENOCKITE— See  Cadmium. 

GREEN  OIL — A  heavy,  crude,  creosote  oil  distilled  from  coal 
tar.  (See  Coal.) 

GREEN  VITRIOL  (Copperas)— Common  name  for  ferrous 
sulphate.  (See  Iron.) 

GREY  ANTIMONY  ORE  (Stibnite)— See  Antimony. 
GRINDSTONE — A  highly  cemented,  tough,  natural  sandstone. 

GROUND-NUT  OIL  (see  Arachis  Oil) — Ground-nuts  are  now 
cultivated  in  China  to  a  considerable  extent. 

GUAIACOL— C-H8O2  or  C6H4(OH)(OCH3)— is  a  phenolic 
compound,  found  present  in  beechwood  tar,  and  is  pro- 
duced along  with  other  substances  by  the  dry  distillation  of 
guaiacum  resin.  (See  Guaiacum.)  It  is  a  colourless,  re- 
fractive, inflammable,  oily  body  of  peculiar  faint  odour, 
reminding  of  creosote ;  of  sp.  gr.  1*1395,  soluble  in  alcohol, 
and  used  in  medicine. 

GUAIACOL  CARBONATE  (C15H14O5  or  (C6H4OCH3)2,CO3),  a 
white,  crystalline  powder  soluble  in  alcohol  and  ether,  is 
used  as  a  non-irritating  preparation  in  the  treatment  of 
phthisis,  diarrhoea,  and  typhoid  fever,  acting  as  an  anti- 
pyretic and  antiseptic. 

GUAIAC-WOOD  OIL— A  thick,  viscid  oil,  apt  to  become 
crystalline,  distilled  from  the  wood  of  some  species  of 
guaiacum,  known  as  "  balsam  wood  "  in  South  America. 
It  is  soluble  in  alcohol  and  ether,  has  a  sp.  gr.  of  about 
0*96  to  0*98,  with  optical  rotation  -  6°  to  7°,  and  is  used  in 
perfumery. 


GUAIACUM—GUMS  237 

GUAIACUM — A  resinous  exudation  from  incisions  made  in 
the  stems  of  the  Guajacum  officinale,  a  tree  which  grows  in 
Jamaica  and  other  West  Indian  islands.  It  is  soluble  in 
alcohol,  acetone,  and  ether,  acts  as  a  mild  laxative  and 
diuretic,  and  is  used  in  the  form  of  lozenges  and  pastilles 
for  throat  troubles,  also  in  varnish-making.  An  optically 
active  substance  named  guaiaretic  acid  (C2pH24O4)  has 
been  isolated  from  the  resin.  (See  Lignum  Vitae.) 

GUANO — Excrement  of  sea-fowl  from  islands  near  the  coast 
of  Peru  and  Chili,  consisting  largely  of  calcium  phosphate, 
and  used  as  a  fertiliser.  (See  Coprolites.) 

GUMS — The  generic  name  of  a  number  of  vegetable,  gummy 
products — that  is  to  say,  more  or  less  sticky — some  of  which 
are  of  the  nature  of  carbohydrates. 

Gum  Accroides  (Black-boy  Gum) — A  resin  from  xan- 
thorrhea-trees,  grown  in  Australia ;  soluble  in  alcohol,  and 
used  in  varnish-making. 

Gum  Ammoniacum  is  really  a  natural  resin  obtained  from 
the  Dorema  ammoniacum. 

Gum  Anime — See  Anime. 

Gum  Arabic  (Acacia)  is  the  dried  juice  from  the  bark  of 
various  species  of  Acacia  which  flourish  in  Arabia,  Egypt, 
and  Senegambia.  It  dissolves  slowly  in  water,  and  consists 
mainly  of  a  mixture  of  alkali  arabinates,  the  arabinic  acid 
comprising  a  combination  of  a  simpler  acid  named  arabic 
acid  in  association  with  two  sugar-like  bodies  named 
arabinose  and  galactose.  The  formula  as  follows,  generally 
represents  the  combination  named  arabinic  acid — 

2(C10H1608),  4(C12H20010)  C23H30018. 
Arabinose.          Galactose.        Acid  Group. 

It  is  used  not  only  as  an  adhesive,  but  also  in  the  prepara- 
tion of  a  number  of  pharmaceutical  and  chemical  emulsions; 
for  thickening  ink  and  blacking,  and  in  calico  printing. 

Gum  Benzoin — See  Benzoin  Gum. 

Gum  Cowrie — See  Kauri. 

Gum  Copal — See  Copal  Gum. 

Gum  Dammar — See  Dammara  resin. 

Gum  Elemi  is  really  a  resinous  East  and  West  Indian 
product  obtained  from  various  terebinthinous  trees,  includ- 
ing the  Amyris  elemifera  (Dutch  Settlements),  and  is  used  in 
making  varnishes  and  lacquer. 

Gum  Kauri — See  Kauri. 


238  G  UMS—G  UTTA  -PERCH  A 

GUMS  (Continued)— 

Gum  Manila — A  copal  variety  of  resin  from  the  Philip- 
pines, of  sp.  gr.  i -06,  and  melting  at  from  230°  to  260°  C. ; 
soluble  in  alcohol  and  ether,  and  used  in  making  paints 
and  varnishes. 

Gum  Mastic — See  Mastic. 

Gum  Sandarach — See  Sandarach. 

Gum  Senegal  .is  obtained  from  a  species  of  acacia  in 
Senegal  and  makes  a  stronger  mucilage  than  gum  arabic 
(acacia).  It  is  used  for  thickening  the  colours  and  mor- 
dants used  by  calico  printers. 

Gum  Thus  is  really  a  resin  and  is  not  soluble  in  water. 
(See  Turpentine.) 

Gum  Tragacanth  is  an  exudation  from  the  Astragalus  vevus 
tree  which  grows  in  Armenia  and  Persia.  It  swells  up  in 
water  and  half  of  it  is  soluble,  and  the  other  part,  consisting 
of  starch,  etc.,  also  dissolves  or  mostly  so  upon  boiling.  It 
contains  about  53*3  per  cent,  arabin  and  is  used  in  medicine, 
by  pharmacists  for  making  emulsions,  and  in  calico  print- 
ing. 

The  cherry-tree  furnishes  a  somewhat  similar  gum. 

British  Gum  (Dextrine)  is  prepared  from  starch  by  the 
action  of  a  small  quantity  of  acid  at  a  temperature  of  about 
150°  C.  The  action  of  malt  extract  upon  starch  also 
produces  dextrine  (C6H10Og)  in  association  with  dextrose. 
(See  also  Mucilage  and  Resins.) 

Yacca  Gum — See  Yacca. 

GUN-COTTON  (Pyroxilin)  is  probably  a  hexanitrated  cellulose, 
whereas  collodion  is  a  tetranitrate  of  cellulose.  (See 
Explosives.) 

GUN-METAL— See  Copper. 
GUNPOWDER— See  Explosives. 

GUTTA-PERCHA — A  natural,  dark,  hardened  juice  of  the 
Sapotacea  or  gutta-percha  trees  (Isonarda  pevcha  or  Isonarda 
gutta)  which  grow  in  Borneo,  Brazil,  Malay,  Singapore, 
Ceylon,  etc.  It  exudes  from  incisions  made  in  the  bark, 
and  in  a  pure  state  is  white,  insoluble  in  alcohol  but  soluble 
in  carbon  disulphide,  turpentine,  and  ether.  It  becomes 
soft  and  impressionable  when  warmed  in  hot  water,  melts 
at  about  120°  C.,  and  is  largely  used  as  an  insulating 
material  for  covering  cables  and  electric  wires,  as  a  covering 
for  golf  balls,  in  dentistry ;  for  making  bottles,  funnels, 


G  UTTA  -PERCH  A  —HA  RTSHORN  239 

GUTTA-PERCHA  (Continued)— 

jugs,  taps,  valves,  and  many  other  articles.  Gutta-percha 
is  a  hydrocarbon,  having  near  chemical  relationship  to 
turpentine  and  rubber. 

GYPSUM— See  Calcium. 

HABEE  PROCESS— See  Nitrogen  Fixation. 

H^BMATINE — The  red  colouring  matter  of  the  blood  is  haemo- 
globin, a  body  of  very  complicated  constitution  consist- 
ing of  haematine  and  albuminous  matters,  and  when 
this  is  dissociated  it  yields  haematine  (C32H32FeN4O6  or 
C34H34FeN4O5),  which  appears  to  be  chemically  related  to 
chlorophyll.  (See  Chlorophyll  and  Respiration.) 

HEMATITE — Iron  ore  of  many  varieties.     (See  Iron.) 
"HAILCRIS" — A    British   white    glass    for    making    miners' 

lamps,  water-tight  fittings,  lamp  globes,  etc. 
"  HAILUXO  "  GLASS— A  British  make  claimed  to  be  equal  to 
the  best  Jena  glass  used  for  making  miners'  glasses  and 
chemical  apparatus,  of  high  heat-resisting  quality. 

HAIR— Consists  of  coalesced  horny  cells  of  a  gelatinous 
character  containing  from  075  to  2  per  cent,  of  mineral  salts. 

HAIR-SALT — A  natural  aluminium  sulphate,  of  fibrous  for- 
mation. (See  Aluminium.) 

HALIDES — Metallic  and  non-metallic  binary  combinations 
of  the  halogens — such  as  sodium  chloride  (NaCl)  and 
silicon  tetrachloride  (SiCl4). 

HALOGENS — The  group  of  chemical  elements  consisting  of 
chlorine,  iodine,  bromine,  and  fluorine,  so  named  because 
they  form  compounds  with  metals  analogous  to  sea-salt 
(sodium  chloride).  In  their  general  character,  they  resemble 
each  other,  and  by  combination  with  hydrogen  they  form 
respectively  hydrochloric,  hydriodic,  hydrobromic,  and 
hydrofluoric  acid  (HC1,  HI,  HB,  and  HF). 

HALOGEN  DERIVATES  of  organic  bodies  are  formed  by  the 
replacement,  for  example,  of  hydroxyl  (HO)  by  a  halogen  ; 
thus  ethyl  alcohol  by  the  action  of  hydrobromic  acid  is 
converted  into  ethyl  bromide — 

C2H6OH  +  HBr  =  C2H5Br  +  H2O. 

HALOIDS — Salts  composed  of  halogen  elements  with  metals, 
such  as  sodium  chloride  and  potassium  iodide. 

HARTSHORN — An  old  name  for  crude  ammonium  carbonate 
as  originally  obtained  by  distillation  of  horn  shavings. 


240  HA  USMA  NNITE—HEA  T 

HAUSMANNITE— A  mineral-red  manganese  oxide  (Mn3O4). 

HEAT — The  view  taken  by  Sir  Isaac  Newton,  and  still 
generally  accepted,  concerning  the  nature  of  heat,  is  that  it 
has  its  origin  in  the  internal  motions  of  the  particles  of 
bodies — that  is  to  say,  movements  or  vibrations  caused 
by  the  exercise  of  energy. 

Just  as  the  sun  is  the  chief  source  of  light,  so  also  it  is 
the  chief  source  of  heat.  Heat  can  be  produced  by  friction, 
as  is  experienced  in  the  use  of  machinery,  when  the  parts 
of  metal  rubbing  against  each  other  are  known  to  become 
very  hot.  An  indefinitely  large  amount  of  heat  can  be 
generated  by  subjecting  a  mass  of  brass  to  friction,  and  this 
is  illustrated  by  the  great  heat  that  is  produced  in  the  boring 
of  metals.  As  another  instance,  it  may  be  stated  that,  when 
two  pieces  of  ice  are  rubbed  together,  sufficient  heat  is  pro- 
duced to  melt  the  ice. 

In  all  chemical  interactions  or  changes,  heat  is  either 
given  out  or  disappears.  When  quicklime  is  mixed  with 
water  (slaked)  it  combines  therewith,  forming  a  hydroxide, 
and  considerable  heat  is  developed,  as  evidenced  by  the 
generation  of  steam.  In  most  cases,  there  is  an  evolution 
of  heat,  but  in  others  it  is  necessary  to  apply  heat  to  bring 
about  the  desired  chemical  change. 

Compounds  in  the  formation  of  which — hydrochloric  acid, 
for  example — heat  is  developed,  are  termed  exothermic, 
and  those  in  which  heat  disappears — carbon  disulphide, 
for  example — are  styled  endothermic  in  character. 

The  heat  of  the  human  body  is  produced  by  the  chemical 
changes  that  are  always  going  on  in  it  during  life. 

Light  can  be  changed  into  heat,  and  heat  has  a  definite 
mechanical  equivalent.  Electricity  can  also  be  converted 
into  heat  and  light,  as  evidenced  by  the  ordinary  electric 
lamps  when  in  use  for  lighting  purposes,  which  then 
become  hot.  According  to  prevalent  ideas,  an  electric 
current  produces  heat  in  a  conductor  because  the  drift- 
energy  of  the  electrons  is  to  some  extent  converted  into 
irregular  motion  energy  by  their  collision  with  the  atoms  of 
the  conductor.  The  same  change  is  utilized  in  a  larger 
degree  in  the  construction  of  electric  radiators  (for  warming) 
and  electrical  furnaces. 

When  solid,  liquid,  or  gaseous  substances  are  heated, 
they  for  the  most  part  enlarge  or  expand,  and  when  cooled 
they  contract.*  The  wheelwright  makes  use  of  this  know- 

*  Ice  may  be  very  much  colder  than  the  surrounding  water,  but  it 
floats.  Water  has  a  maximum  density  at  4°  C.,  but  if  cooled  below 
or  heated  above  this  temperature,  it  expands  ;  and  but  for  this,  in  case 


HEAT  241 

HEAT  (Continued)— 

ledge  in  affixing  iron  tyres  to  wheels,  by  placing  them  round 
the  wheels  when  in  a  very  heated  condition,  so  that  upon 
cooling  they  clamp  by  contraction  and  hold  tight  to  the 
wooden  rims.  But,  on  the  other  hand,  some  metals  and 
alloys  expand  at  the  moment  of  setting,  and  thus  give  a 
sharp  casting,  whereas  others  contract  at  the  moment  of 
setting  and  in  consequence  give  a  bad  casting. 

Many  solid  substances,  such  as  sulphur,  camphor,  naph- 
thalene, and  iodine,  can  be  sublimated  by  heat — that  is  to 
say,  they  can  be  converted  into  the  state  of  vapour,  and 
when  the  vapour  is  cooled,  the  substance  is  redeposited  in 
the  solid  form — a  sort  of  dry  distillation. 

Again,  many  liquid  bodies,  such  as  water,  can  be  distilled 
— i.e.,  boiled  and  thereby  converted  into  vapour,  and  when 
the  vapours  are  cooled  again,  they  condense  once  more 
into  the  original  liquid  forms.  Ether,  alcohol,  turpentine, 
and  many  other  liquids,  can  be  distilled  in  this  way,  and  the 
process  is  often  used  for  purifying  the  substances  employed 
from  associated  impurities. 

The  temperatures  at  which  liquids  boil  or  become 
vaporized  are  known  as  their  boiling-points,  and  these 
are  registered  by  thermometers.  The  temperature  at  which 
solid  or  metallic  bodies  melt  are  known  respectively  as 
their  melting  or  fusing  points. 

Ether  boils  at  35-6°  C. ;  alcohol  at  78-4°  C. ;  water  at 
100°  C. ;  turpentine  at  160°  C. ;  and  mercury  at  about 
350°  C. 

Temperatures   are  usually  determined   in   this   country 
according  to  two  scales,  but  chemists  for  the  most  part  use 
;what  is  called  the  Centigrade  or  C.  scale  ;   the  other  is 
known   as  the   Fahrenheit   or    F.     In  Russia,   Italy,   and 
Austria  there  is  still  another  scale,  known  as  the  Reaumur 
or    R.     On    the    Centigrade   scale,    the   freezing-point   of 
water  is  regarded  as  zero  (p°),  and  the  boiling-point  is  100° ; 
whereas  on  the  Fahrenheit  scale,  the  freezing-point  is  32°, 
and  the  boiling-point  is  212°. 

To  convert  a  Centigrade  reading  into  a  Fahrenheit  read- 
ing, multiply  by  9,  divide  by  5,  and  then  add  32.  To 
convert  a  Fahrenheit  reading  into  a  Centigrade  reading 
subtract  32,  multiply  by  5  and  divide  by  9. 


of  great  cold,  our  lakes  and  rivers  might  become  frozen  solid  to  the 
bottom.  If  water  had  not  this  peculiar  property  our  climate  would  be 
of  arctic  character  and  a  large  part  of  the  world  would  be  unin- 
habitable. 

16 


242  HEAT 

HEAT  (Continued)— 

SOME  NOTABLE  TEMPERATURES. 

Centigrade.  Fahrenheit. 

Theoretical  zero  of  temperature        -  273°  -  459^4° 

Mercury  freezing-point              ...       -38-8°  -37-84° 

Freezing-point  of  water             ...              o°  32° 

Mean  atmospheric  temperature            I5'5°  60° 

Blood  heat...             ...             ...         36-9°  98-4° 

Boiling-point  of  water               ...           100°  212° 

Mercury  boiling-point                ...           35°°  662° 

Pyrites  burners          ...             ...  4oo°-5oo°  752°-932° 

Red  heat  just  visible  in  the  dark           526°  979° 

Gas  producers            ...                 900°-! 300°  i652°- 

Reverberatory  furnaces                9oo°-i4oo°  i6^2°- 

Kilns — for  various  burnings        900°- 1600°  1652° -2912 
Coke  oven  (chambers)               ...          1100° 

Deep  orange  heat       ...             ...          1100°  2012 

Frit  kilns     ...             ...              noo°-i4oo°  2oi2°-2552 

Steel  melting-point     ...             ...          1350°  2462 

Glass-furnace  heat     ..              ...          1375°  25°7° 

White  heat...             ...             ...          1500°  2732° 

Steel  melting  (in  crucibles)       ...         1500°  2732° 

Cast-iron  melting-point             ...          1530°  2786° 

Open  hearth  furnace                 ...         1600°  2912° 

Blast-furnace  heat      ...             ...          1930°  3506° 

Oxy-hydrogen  flame  ...             ...         2800°  5°72° 

Electric  furnace         ...             ...         3600°  6512° 

Arc  lamp     ...             ...             ...         4000°  7032° 


In  the  Reaumur  scale,  the  interval  between  the  freezing 
and  the  boiling  points  of  water  is  divided  into  80°  instead 
of  100°  as  in  the  Centigrade  scale,  so  that  in  this  case, 
while  the  freezing-point  is  o°,  the  boiling-point  of  water 
is  80°.  To  convert  Centigrade  readings  into  Reaumur 
readings,  multiply  by  4  and  divide  by  5  ;  and  to  convert 
Fahrenheit  readings  into  Reaumur  readings,  subtract  32, 
multiply  by  4  and  divide  by  9. 

A  substance  is  said  to  be  a  good  conductor  of  heat  when 
heat  is  easily  transmitted  by  or  through  it.  For  instance, 
if  a  copper  or  iron  wire  be  held  by  the  hand  and  the  other 
end  placed  in  the  flame  of  a  lamp  or  candle,  the  heat  is 
quickly  conducted  from  that  end  to  the  one  held  in  the 
hand  and  can  be  felt. 

A  slab  of  marble  or  metal  feels  colder  to  the  hand  than  a 


HEAT  243 

HEAT  (Continued)— 

block  of  wood,  because  those  substances  are  better  con- 
ductors of  heat  and  more  quickly  take  heat  away  from  the 
hand.  Charcoal  is  an  instance  of  a  bad  conductor,  so  that 
a  short  stick  of  it  can  be  made  red-hot  at  one  end  and  held 
by  the  hand  at  the  other  without  feeling  any  pain.  Air  also 
is  a  bad  conductor,  as  are,  indeed,  all  gases.  The  metals  as 
a  class  are  good  conductors. 

When  water  is  sufficiently  heated  in  a  closed  vessel — 
that  is  to  say,  in  such  a  way  that  the  vapour  or  steam 
cannot  escape — the  temperature  of  the  water  goes  beyond 
its  ordinary  boiling-point  and  any  steam  that  is  generated 
is  held  under  pressure,  the  boiling-point  of  the  water 
increasing  with  the  pressure.  Of  course,  this  can  only  be 
done  in  very  strong  vessels,  otherwise  they  would  explode 
with  violence.  When  water  is  heated  in  this  way  to  a 
temperature  of  121°  C. — that  is,  21°  C.  above  its  ordinary 
boiling-point — the  pressure  of  the  steam  generated  is  equal 
to  30  pounds  on  the  square  inch  (  =  to  2  atmospheres  of 
30  inch  mercury),  and  the  construction  of  steam-engines 
is  based  upon  a  knowledge  of  these  facts.  Steam  under 
pressure  as  generated  in  locomotives,  is  used  to  force  down 
a  piston  in  a  cylinder,  and  this  is  made  to  operate  on 
wheels  with  which  it  is  connected,  in  such  a  way  as  to 
bring  and  maintain  a  train  in  motion. 

This  illustration  will  also  serve  to  explain  again  what 
has  already  been  referred  to  when  describing  force  and 
energy.  The  great  heat  generated  by  the  burning  fuel  used 
under  the  boiler  is  taken  up  by  the  water  and  converted 
into  energy  or  force ;  that  is  to  say,  water  which  at  the 
ordinary  temperature  of  the  air  is  a  quiet,  harmless  liquid, 
can,  by  becoming  heated  in  the  form  of  steam,  assume  an 
energy  so  great  that,  unless  the  boilers  were  made  of 
intensely  strong  material,  it  would  cause  them  to  explode. 
Illustrations  of  the  conversion  of  chemical  action  into 
energy  are  also  afforded  by  the  explosion  of  a  mixture  of 
petrol  vapour  and  air  as  utilized  in  the  engines  of  motor 
vehicles,  and  by  the  use  of  gunpowder.  (See  Gunpowder, 
also  Explosives.) 

Heat  has  often  been  described  as  a  mode  of  motion,  and 
its  mechanical  equivalent  is  expressed  by  the  ascertained  fact 
that  a  weight  of  i  Ib.  falling  through  778  feet  may  produce 
by  friction  or  otherwise,  enough  heat  to  raise  the  temperature 
of  i  Ib.  of  water  i°  F. 

It  is  of  importance  to  note  that  substances  vary  very 
much  in  their  capacity  for  heat.  (See  Specific  Heats.)  For 


244  HEAT 

HEAT  (Continued)— 

example,  water  requires  more  than  twice  as  much  heat  to 
raise  it  to  any  particular  temperature,  as  does  an  equal 
weight  of  quicksilver  (mercury),  and  this  fact  in  itself  is 
a  confirmation  of  the  view  that  matter  and  force  are  one 
and  inseparable.  It  is  all  a  matter  of  state,  and  we  only 
recognize  a  substance  or  any  particular  form  of  matter  by 
the  expressions  or  properties  given  to  it  by  the  forces 
which  control  it — i.e.,  subject  to  which  it  exists  in  any 
particular  phase  or  in  a  particular  environment. 

When  a  gas,  such  as  carbon  dioxide,  is  liquefied — as  it 
can  be — by  cooling  and  pressure,  and  then  allowed  to 
escape  by  a  jet  from  its  container,  some  part  of  the  escap- 
ing gas  will  absorb  heat  from  the  other  part,  causing  it  to 
be  deposited  in  the  solid  form,  resembling  snow.  In  a 
similar  way,  snow  when  lying  on  the  ground,  during  a  thaw, 
will,  by  absorbing  heat  from  its  surroundings,  cause  ice  to 
be  produced  in  its  immediate  vicinity.  (See  Refrigeration.) 

In  passing  from  the  solid  to  the  liquid  state,  there  is  what 
appears  to  be  a  disappearance  of  heat,  so  that  when  solid 
ice  liquefies  to  water,  the  heat  which  thus  disappears  or  is 
rendered  latent  would  suffice  to  raise  the  same  weight  of 
water  through  79°  C.  On  the  other  hand,  when  water  is 
frozen,  this  so-called  heat  of  liquidity  is  evolved,  and  a 
corresponding  evolution  of  heat  takes  place  when  all  sub- 
stances pass  from  the  liquid  to  the  solid  form,  the  amount 
varying  with  the  particular  substances.  Thus,  when  a 
saturated  solution  of  sodium  sulphate  is  suddenly  agitated, 
it  at  once  crystallizes,  and  the  thermometer  will  indicate  an 
immediate  rise  of  temperature. 

Again,  heat  is  rendered  latent  when  substances  pass  from 
the  liquid  to  the  gaseous  state,  as  when,  for  example,  water 
is  converted  into  steam,  the  latent  heat  of  which  is  536 
thermal  units. 

The  British  thermal  unit  is  that  required  to  raise  i  Ib. 
of  water  at  its  temperature  of  maximum  density,  i°  F.  =  250 
gram-calories ;  the  gram-calory  being  the  amount  of  heat 
required  to  raise  i  gram  of  water  through  i°  C. 

Many  chemical  actions  are  brought  about  by  employing 
the  agency  of  heat,  and  nearly  all  kinds  of  combustion  are 
initially  dependent  upon  its  employment.  For  example,  a 
fire  as  laid  in  a  domestic  grate  will  not  burn  unless  heat  in 
the  form  of  a  lighted  match  be  first  of  all  applied  to  it. 

Heat  is  all-powerful,  too,  in  breaking  up  many  chemical 
combinations,  causing,  in  other  words,  the  dissociation  of 
their  component  parts  by  overpowering  the  force  by  which 


HEAT— HELLEBORE  245 

HEAT  (Continued) — 

they  are  previously  united  or  held  together.  Even  steam 
can  be  thus  broken  up  into  its  component  parts  (hydrogen 
and  oxygen  gases)  by  the  agency,  for  example,  of  a  piece 
of  platinum  metal  intensely  heated. 

HEAVY  SPAR— Barium  sulphate  (BaSO4). 

HEDERIC  ACID — A  derivative  prepared  from  a  glucoside 
(Hederin)  contained  in  ivy  leaves  and  seeds  (Hedeva  helix). 

HEHNER  VALUE  (of  fats,  oils,  and  waxes)  represents  the 
percentage  of  insoluble  fatty  acid  +  the  non-saponifiable 
constituents. 

HELIOTROPIN  (Piperonal)  (CH2O2  :  C6H3.CHO)  —  A  white, 
shining,  crystalline  substance  prepared  synthetically  from 
safrol  and  piperine,  and  used  in  medicine  and  perfumery. 
Mixed  with  vanillin  it  is  sold  as  "  white  heliotrope." 

HELIUM  (He)  —  Atomic  weight,  4 ;  melting-point  below 
-  271°  C.  It  was  previously  known  as  a  constituent  of  the 
sun's  atmosphere,  but  much  more  recently  recognized  as 
present  in  the  air  in  extremely  minute  quantity  (i  to  2 
volumes  in  1,000,000)  and  in  certain  mineral  spring  waters, 
notably  those  of  Bath.  It  is  also  found  in  association  with  a 
large  nuniber  of  mineral  compounds  of  uranium,  thorium, 
and  other  rare  earths,  including  cleveite  and  uraninite  (pitch- 
blende). It  is  a  colourless  gas  of  very  light  character 
(density  2),  ranking  next  to  hydrogen  in  this  respect.  It 
is  also  said  to  be  a  disintegration  product  of  radium  emana- 
tion ;  but  if  that  be  correct,  then,  of  course,  radium  cannot 
be  regarded  as  an  element.  In  common  with  the  other 
members  of  the  argon  group  it  is  very  inert  and  practically 
devoid  of  chemical  characters.  Certain  wells  of  natural  gas 
in  many  parts  of  the  world  contain  small  proportions  of 
helium  and  some  in  Texas  contain  from  i  to  2  per  cent. 
This  has  been  produced  in  large  quantities  to  fill  airships, 
having  the  advantages  over  hydrogen  of  being  non-inflam- 
mable and  non-explosive.  (See  Radium  and  Lead.) 

There  is  also  a  natural  gas-supply  at  Hamilton,  Ontario, 
from  which  it  has  been  found  practicable  to  isolate  helium 
of  97  per  cent,  purity  on  a  commercial  scale,  at  a  cost  of 
less  than  2^-d.  per  cubic  foot. 

HELLEBORE  as  obtained  from  the  root  of  the  black  variety 
(Helleboms  niger)  contains  a  nitrogenous,  crystalline  sub- 
stance soluble  in  alcohol,  named  helleborine.  Pharma- 
ceutical preparations  are  made  from  the  roots  of  the  white 
and  green  hellebores. 


246  HEM  A  TINE-  HESPERIDENE 

HEMATINE — A  colouring  matter  prepared  in  the  forms  of 
crystals,  paste,  and  liquor  from  logwood  extract,  and  not  to 
be  confounded  with  the  red  colouring  matter  of  blood 
corpuscles  (haematine). 

HEMLOCK  (Conium  maculatum)  contains  an  active,  narcotic,  alka- 
loidal  principle  known  as  coniine  (C8H17N),  a  colourless,  oily 
body,  soluble  in  water,  alcohol,  and  ether,  which  can  also 
be  produced  by  artificial  processes.  (See  Logwood  Extract.) 

HEMP8EED  OIL  is  obtained  by  pressing  or  extraction  from 
hempseed  (Canndbis  sativa),  and  is  of  faint  green  colour, 
non-drying  in  character,  and  turns  brownish-yellow  upon 
standing.  It  has  a  sp.  gr.  of  0*925  to  0*928,  a  saponifica- 
tion  value  of  about  192*5,  and  an  iodine  value  of  148.  It  is 
soluble  in  ether,  benzol,  and  carbon  disulphide,  and  is  used 
for  illuminating  purposes  and  in  making  soft  soaps,  paints, 
and  varnishes. 

HENBANE— from  Hyoscyamus  niger — A  poisonous  plant  con- 
taining two  alkaloids  named  hyoscyamine  (a  white,  crys- 
talline alkaloid  (C17H23NO3))  and  hyoscine  (an  uncrys- 
tallizable  alkaloid  (C17H21NO4)).  The  plant  is  stated  to 
grow  wild  on  the  north  coast  of  Somerset. 

Hyoscine  is  a  powerful  narcotic  and  hyoscyamine 
exhibits  mydriatic  action.  Wild  Manchurian  henbane 
seeds  (ten-sen-si)  have  been  found  recently  to  contain 
scopolamine  instead  of  hyoscyamine. 

HENNA  (Al-Kenna) — The  root  and  leaves  of  Lawsonia  inermis, 
employed  in  the  East  to  dye  the  nails,  teeth,  hair,  and 
garments.  A  recent  investigation  has  revealed  the 
presence  of  a  crystalline  orange-yellow  colouring  matter  in 
the  leaves,  which  is  soluble  in  water,  and  dyes  wool  and 
silk.  With  alkalies  it  gives  a  bright  orange-red  colouration, 
and  has  the  composition  C10H6O3. 

HEPTANE— See  Hydrocarbons. 

HEPTYL— See  Alcohols. 

HEPTYLENE  (C7H14) — A  hydrocarbon  of  the  olefine  series. 

HERMETICAL  SEAL — The  closure  of  a  hollow  vessel  by 
melting  or  cementing  the  lips  of  its  orifice  or  opening. 
Thermometers  are  hermetically  sealed. 

HEROIN  (Diacetylmorphine) — A  white,  crystalline,  poisonous  de- 
rivative of  morphine,  used  in  medicine ;  melting-point,  1 7 1  ° C. 

HERRING  OIL— See  Fish  Oils. 

HESPERIDENE  —  A  terpene  constituent  of  oil  of  orange. 
(See  Essential  Oils.) 


HEX  A  MINE— HONE  Y -STONE  247 

HEXAMINE  (C6H12N4)  —  A  white,  crystalline  substance, 
soluble  in  water  and  alcohol,  prepared  by  the  action  of 
formaldehyde  on  ammonia,  and  used  as  an  internal  dis- 
infectant for  the  urinary  system,  the  acid  of  the  urine 
converting  it  into  formaldehyde.  It  was  used  in  masks  as 
an  absorbent  for  phosphene  gas  in  the  recent  war. 

HEXANE— See  Hydrocarbons. 

HEXOSES — A  group  of  carbohydrates,  including  the  sugar-like 
constituents  of  ripe  fruits  (a-glucose,  a-fructose,  etc.). 

HEXYLENE  (C6H12)— A  hydrocarbon  of  the  olefine  series. 
HIGH-BOILING  TAR  ACIDS— See  Phenoloids. 

HIPPURIC  ACID  (C9H9NO3)— A  constituent  of  the  urine  of 
horses,  being  an  amino-derivative  of  benzoic  acid,  which  is 
converted  into  hippuric  acid  in  passing  through  the  animal 
body.  It  is  a  white,  crystalline  body,  of  melting-point 
about  190°  C. ;  easily  soluble  in  alcohol  and  hot  water. 

HOLLANDS — A  gin-like  spirit  made  in  Holland  from  grain. 

HOLMIUM  (Ho) — Atomic  weight,  163-5.  A  recently  dis- 
covered, very  rare  element  of  the  yttrium  group  occurring 
in  the  minerals  thulium,  gadolinite,  samavskite,  etc.  Its  com- 
pounds are  but  little  known. 

HOMATROPINE  (C16H21NO3)— A  white,  crystalline,  poisonous 
base  allied  to  atropine,  which  melts  at  95*5°  C.  and  exercises 
a  mydriatic  action  or  power  of  dilating  the  pupil  of  the  eye. 

HOMATROPINE  HYDROBROMIDE  (C16H22NO3Br)— A  white, 
crystalline  salt,  soluble  in  water  and  alcohol,  used  to  dilate 
the  pupil  of  the  eye ;  melting-point,  213-8°  C. 

HOMOGENEOUS — Of  uniform  composition. 

HOMOLOGUES — Substances  having  a  relative  or  corresponding 
position  in  a  series  of  analogous  bodies.  For  example, 
the  paraffins,  the  olefines,  and  the  alcohols  are  homologous 
series  rising  in  degrees  of  the  constituent  or  radical  group 
CH2.  Substances  belonging  to  such  series  exhibit,  more 
or  less,  gradations  of  many  properties  and  boiling-points. 
(See  Alcohols  and  Hydrocarbons.) 

HONEY  contains  cane  sugar  and  from  61  to  75  per  cent,  of  a 
glucose  named  grape  sugar  or  dextrose. 

HONEY-STONE  (C12Al2O12,i8H2O)  —  A  crystallized  native 
mellitate  of  aluminium  occurring  in  lignite  found  in 
Thuringia,  Bohemia,  and  Moravia. 


248  HOP—HUBNERITE 

HOP — The  fruit  of  this  plant  (Humulus  lupulus]  contains  a 
yellow,  bitter  powder  named  lupulin,  of  mixed  constitution 
including  a  resin,  a  waxy  body,  and  extractive  matters, 
and  when  distilled  with  water  it  yields  valerianic  acid  and 
a  volatile  oil.  (See  Oil  of  Hops.)  The  real  bitter  principle 
is  said  to  form  about  from  8  to  12  per  cent,  of  the  lupulin 
powder  of  which  the  hop  fruit  contains  about  10  per  cent., 
and  includes  an  acid  named  humulon. 

"HOPOL  POWDER" — A  proprietary  preparation  to  make 
liquid  metal  polish  by  mixing  with  a  turpentine  substitute. 

HOPS  (OIL  OF)  is  obtained  from  hop  cones  which  yield  it  upon 
distillation  with  water,  being  derived  from  the  lupulin  or 
yellow  bitter  powder  which  is  contained  in  them,  to  the 
extent  of  from  about  8  to  12  per  cent.  It  is  green  in  colour, 
has  the  odour  of  thyme,  and  is  said  to  contain  geraniol  and 
a  terpene.  It  is  soluble  in  alcohol  and  ether  and  has  a 
sp.  gr.  0-855  to  0'88o. 

HORMONES — A  class  of  substances  secreted  by  special  glands 
in  the  living  body  and  regarded  as  essentials  to  perfect 
nutrition  to  the  extent  of  something  less  than  i  per  cent. 
of  the  food. 

One  of  these  substances  is  named  thyroxin,  and  is 
secreted  by  the  thyroid  gland,  but  its  chemical  nature  and 
constitution  are  not  at  present  fully  ascertained.  Another 
is  secreted  by  the  salivary  glands,  and  a  third  is  choline. 
which  is  found  in  the  alimentary  and  intestinal  tracts  of 
animals.  These  hormones  are  not  proteins,  and  are  usually 
soluble  in  alcohol  and  ether,  but  they  are  probably  nearly 
allied  to  the  substances  referred  to  under  the  heading  of 
Vitamines. 

HORN-BLENDE — A  mineral  consisting  of  compound  silicates  of 
various  metals  (magnesium,  iron,  and  calcium) in  association, 
otherwise  known  as  amphibole. 

HORN-MERCURY  (Horn-Quicksilver) — A  native  form  of  mer- 
curous  chloride  (Hg2Cl2)  (calomel). 

HORN-SILVER  (Cerargyrite)— Native  silver  chloride  (AgCl2) 
found  in  some  of  the  American  States. 

HORSEMINT  OIL  (Monarda  Oil),  distilled  from  the  herb 
Monarda  punctata,  is  yellowish-red,  soluble  in  alcohol  and 
ether,  having  a  sp.  gr.  of  about  0*92  to  0-94,  and  used  in 
compounding  liniments. 

HUBNERITE — Mineral  manganese  tungstate  (MnWO4)  found 
in  certain  American  States. 


HUMIDITY— HYDROCARBONS  249 

HUMIDITY — Moisture  present  in  the  air.  The  temperature 
at  which  air  is  saturated  with  moisture  and  begins  to  deposit 
it  is  known  as  the  dew-point.  (See  Air.) 

HUMUS — Decayed  vegetable  matter  as  found  present  and 
formed  from  cellulose  in  soil,  containing  a  substance  called 
humic  acid,  and  it  is  on  record  that  oxidation  of  phenols 
in  alkaline  solution  leads  to  the  formation  of  substances 
which  have  all  the  properties  of  natural  humic  acids,  one 
of  them  having  the  formula  C6H4O3. 

4*  HYCOL  " — A  phenoloid  disinfectant  emulsifying  with  water. 

HYDRA3TINE  (C21H21O6N)— A  white,  poisonous  alkaloid 
from  the  root  of  Hydrastis  canadensis,  used  in  medicine.  By 
oxidation  it  yields  hydrastinine  (C^t^OgN),  which  is  also 
used  in  medicine;  melting-point,  131°  C. 

HYDRATES— See  Bases. 

HYDRIDES — A  term  given  to  a  number  of  combinations  of 
hydrogen  with  metals  such  as  arsenic  hydride  (AsH3)  and 
lithium  hydride  (LiH) ;  also  to  combinations  of  hydrogen 
with  alcohol  radicals  such  as  ethyl  hydride  (ethane)  (C2H6 
or  C2H5H). 

HYDRIODIC  ACID— See  Iodine. 
HYDROBROMIC  ACID— See  Bromine. 

HYDROCARBONS  —  Combinations  of  carbon  and  hydrogen, 
constituting  a  large  body  of  organic  compounds  of  great 
interest  and  importance.  The  more  important  ones  may 
be  roughly  classified  as  follows  : 

(i)  The  Paraffins — a  series  of  homologous  saturated  hydro- 
carbons of  which  the  lower  and  best-known  members  are — 

Methane  (CK4)  with  a  boiling-point  of  -  164°  C.  and 

sp.  gr.  0-415  at  boiling-point. 
Ethane  (C2H6)  with   a  boiling-point  of  -  84°  C.  and 

sp.  gr.  0-446  at  o°  C. 
Propane  (C3H8)  with  a  boiling-point  of  -  37°  C.  and 

sp.  gr.  0-536  at  o°  C. 
Butane  (C4H10)  with   a  boiling-point  of  +   i°  C.  and 

sp.  gr.  0*600  at  o°  C. 
Pentane    (C5H12)   with    a  boiling-point  of  37°  C.  and 

sp.  gr.  0-627  at  I4°  C. 
Hexane  (C6H14)    with   a   boiling-point  of  69°   C.  and 

sp.  gr.  0-658  at  20°  C. 
Heptane  (C7H16)   with  a  boiling  point  of  98°  C.   and 

sp.  gr.  0-683  at  20°  c- 


250  HYDROCARBONS— HYDROCHLORIC  ACID 

HYDROCARBONS  (Continued)— 

These  hydrocarbons  exhibit  a  step-by-step  rise  of  CH2 
and  a  gradual  rise  in  the  specific  gravities. 

Under  suitable  conditions  they  can  be  oxidized  by  air  to 
fatty  acids. 

Methane  is  a  constituent  of  "  marsh  gas "  and  "  fire- 
damp," and  often  results  from  the  decomposition  of  organic 
matter  under  water.  Coal  gas  contains  about  40  per  cent, 
methane.  It  burns  with  a  faintly  luminous  flame  and 
forms  an  explosive  mixture  with  air  or  oxygen. 

Ethane  is  a  gas  contained  in  crude  petroleum  and 
can  be  prepared  by  the  electrolysis  of  acetic  acid  and  other- 
wise. Like  methane  it  burns  with  a  slightly  luminous 
flame. 

Propane  and  Butane  are  also  gases,  while  the  next  three 
members  of  the  series  are  colourless,  mobile,  inflammable 
liquids  with  boiling-points  as  above  set  forth,  found  in 
paraffin  oil  as  obtained  from  cannel-coal  and  in  petro- 
leum oil. 

Pentane  is  a  colourless,  mobile,  inflammable,  pleasant- 
smelling  liquid  soluble  in  alcohol  and  ether,  and  can  be 
obtained  by  the  fractional  distillation  of  petroleum.  It  is 
sometimes  used  as  an  anaesthetic,  and  in  the  artificial 
manufacture  of  ice. 

The  liquid  paraffins  are  all  soluble  in  alcohol  and  ether 
but  not  in  water. 

(2)  The  Olefines  or  Ethylene  series  are  described  under 
that  heading. 

(3)  The  Acetylene  series  of  general  formula  CwH2w_2  con- 
tain 2  atoms  of  hydrogen  less  than  the  olefines,  including 
acetylene  (C2H2),  which  is  separately  described. 

(4)  The  Benzene  Hydrocarbons,  of  which  the  best-known 
members  are — 

Benzene  (C6H6),  which  boils  at  80-4°  C.  and  has  a 
sp.  gr.  of  o'874. 

Toluene  (C?H8),  which  boils  at  110°  C.  and  has  a 
sp.  gr.  of  0*869. 

Xylene  (C8H10),  of  which  there  are  several  modifica- 
tions. (See  also  Benzene,  Toluene,  and  Xylene.) 

(5)  A  group  having  a  benzene  nucleus  including  naph- 
thalene (C10H8)  and  anthracene  (C^H^)  ;  and 

(6)  The   Terpenes  (C10H16),  which   are  described  under 
that  heading. 

HYDROCHLORIC  ACID— See  Chlorine. 


HYDROCYANIC  ACID— HYDROGEN  251 

HYDROCYANIC  ACID  or  PRUSSIC  ACID  (HCN)  is  a  colour- 
less gas  of  peculiar  odour  like  that  of  bitter  almonds,  and 
is  intensely  poisonous.  It  is  prepared  by  the  action  of 
dilute  sulphuric  acid  upon  potassium  cyanide  (from  which 
mixture  the  acid  can  be  distilled  over  with  the  water),  or 
in  a  pure  state  by  passing  hydrogen  sulphide  over  dry 
mercuric  cyanide — 

Hg(CN)2  +  H2S  =  2(HCN)  +  HgS. 

In  liquid  form  the  pure  acid  is  a  volatile  fluid  which 
boils  at  26-5°  C.  and  solidifies  at  — 15°  C.  Upon  keeping, 
it  undergoes  change  into  ammonium  formate — 

HCN  +  aH20  =  NH4CH02. 

It  is  soluble  in  water,  alcohol,  and  ether,  and  by  combina- 
tion with  bases,  forms  cyanides ;  a  large  number  of  double 
cyanides  are  also  known. 

The  most  important  commercial  cyanogen  compound  is 
potassium  cyanide.  (See  also  Amygdalin.) 

HYDROFLUORIC  ACID— See  Fluorine. 

HYDROFLUOSILICIC  ACID— See  Silicon. 

HYDROGEN  (H)  and  its  Compounds  —  Atomic  weight,  i  ; 
melting-point,  -  259°  C.  Hydrogen  does  not  exist  to  any 
considerable  extent  in  nature  in  the  free  gaseous  state, 
although  it  is  believed  to  be  present  in  very  large  amount 
in  the  atmosphere  of  the  sun.  At  ordinary  temperatures 
it  is  a  colourless  gas,  soluble  to  some  extent  in  water 
(i  volume  of  which  at  o°  C.  dissolves  0*021  volume  of  the 
gas),  is  without  taste  or  smell,  and  is  the  lightest  known 
substance,  so  that  the  relative  weights  of  all  other  elements 
and  substances  are  generally  compared  with  hydrogen  as 
the  unit. 

In  its  ordinary  form  hydrogen  is  a  comparatively  inactive 
substance,  but  it  can  be  prepared  in  an  activated  state  by 
the  action  of  alpha  rays,  or  by  heating  a  metallic  filament 
in  the  gas  at  low  pressure,  also  in  the  explosion  of  oxy- 
hydrogen  mixtures  by  the  silent  electric  discharge.  In  this 
active  form  it  is  capable  of  reducing  potassium  perman- 
ganate to  the  lower  manganate,  indigo  blue  to  indigo  white, 
and  combining  with  nitrogen  to  form  ammonia.  This 
activated  hydrogen  is  regarded  as  triatomic,  and  is  some- 
times described  as  "  hyzone  "  (H3).  It  is,  however,  very 
unstable,  and  is  stated  to  revert  to  the  inactive  state  in 
less  than  one  minute. 

Hydrogen  gas  is  inflammable,  and  when  a  stream  of  it  is 
burned  in  the  air  or  oxygen  gas  it  forms  water  by  combina- 
tion, thus : 


252  HYDROGEN 

HYDROGEN  (Continued)— 

In  recent  years,  hydrogen  has  been  reduced  to  the  liquid 
state,  in  which  it  is  as  clear  and  colourless  as  water. 

The  gas  is  most  easily  made  in  the  laboratory,  by  the 
action  of  dilute  sulphuric  acid  upon  the  metal  zinc,  thus  : 

Zn  +  H2SO4  =  ZnSO4  +  H2 

— that  is  to  say,  the  metal  is  attacked  and  dissolved  by  the 
acid,  forming  zinc  sulphate,  which  passes  into  solution,  the 
hydrogen  escaping  in  the  form  of  gas. 

A  mixture  of  hydrogen  and  oxygen  gas  (or  air)  in  certain 
proportions,  will  explode  when  a  light  or  electric  spark  is 
applied  to  the  mixture,  water  being  thus  produced  in  the 
same  way  as  when  a  stream  of  hydrogen  is  burned  in 
the  air. 

Hydrogen,  prepared  by  various  industrial  processes, 
is  now  largely  used  in  the  oxy-hydrogen  flame  for 
welding,  also  to  fill  the  bags  or  floating  chambers  of  air- 
ships, zeppelins,  etc.,  and  in  a  number  of  industries,  in- 
cluding the  hydrogenation  of  oils  for  use  in  soap-making. 
Oils  treated  by  this  process  are  converted  into  solid  fats  by 
the  assimilation  or  absorption  of  hydrogen ;  for  example, 
oleic  acid  (C18H34O2)  absorbs  2  atoms  hydrogen,  and 
becomes  converted  into  stearic  acid  (C18H36O2). 

The  hydrogen  for  this  purpose  may  be  prepared  either  by 
passing  the  vapour  of  water  over  iron  prepared  in  a  spongy 
condition,  at  a  high  temperature,  by  which  the  oxygen  is 
made  to  combine  with  the  iron  and  the  hydrogen  gas  is  set 
free  ;  or  by  the  electrolysis  of  water,  in  which  process  the 
hydrogen  is  evolved  at  one  pole  of  the  generator  and  the 
oxygen  at  the  other. 

The  "  Silicol "  process  consists  in  the  decomposition  of 
silicon  alloys,  such  as  ferro-  or  mangano-silicons  (obtained 
in  the  electric  furnace),  by  a  strong  solution  of  caustic  soda, 
containing  from  35  to  40  per  cent,  of  NaHO,  the  heat 
generated  by  the  soda  solution  being  sufficient  to  start  the 
reaction — 

Si  +  2NaOH  +  H20  =  Na2SiO3  +  2H2. 

Another  method  of  preparing  hydrogen  is  by  the  action 
of  water  on  an  alloy  of  magnesium  and  lead. 

The  Linde- Frank-Car  o  process  operates  by  liquefying  all 
the  constituents  of  water  gas  except  hydrogen. 

Another  process  depends  upon  the  oxidation  of  the  carbon 
monoxide  of  water  gas,  and  then  separating  the  carbon 
dioxide  thus  formed  from  the  remaining  hydrogen  by 
under  pressure  through  water. 


HYDROGEN— HYDROGEN  DIOXIDE  253 

HYDROGEN  (Continued)— 

The  hydrogenation  of  oils  is  brought  about  by  the  influence 
of  so-called  catalytic  agents,  the  metal  nickel  (varying  in 
amount  from  0^25  to  i  per  cent,  of  the  weight  of  the  oil) 
being  mostly  used  for  this  purpose,  although  palladium, 
platinum,  cobalt,  and  other  metals,  can  be  used. 

The  catalytic  agent  is,  of  course,  brought  into  contact 
with  the  oils  to  be  treated  and  the  hydrogen  at  the  same 
time,  and  there  are  many  modifications  of  plant  for  bringing 
this  about. 

Many  oils  such  as  whale  oil,  otherwise  difficult  to  purify 
and  having  objectionable  properties,  are  thus  deodorized 
and  turned  into  solid  fats  more  easily  and  economically 
adapted  for  soap-making,  or  made  fit  for  edible  use, 

Fat  hardening  in  Switzerland  is  chiefly  conducted  with 
the  oils  obtained  by  cold  pressure  from  sesame  seed  and 
ground  nuts.  After  refining,  they  are  mixed  with  the 
catalyst  (very  finely  divided  nickel  oxide  or  salt)  and  heated 
to  from  1 00°  to  260°  C.  in  a  high  steam  jacketed  autoclave, 
the  hydrogen  (which  is  prepared  from  water  by  the  electro- 
lytic method — purity  being  essential)  being  introduced 
through  pipes  into  the  mixture. 

Hydrogen  combines  with  oxygen  to  form  two  oxides — 
viz.,  water  (H2O)  and  hydrogen  dioxide  (peroxide) 
(H2O2).  With  the  halogens,  it  forms  the  four  acids 
known  as  hydrochloric  (HC1),  hydrobromic  (HBr),  hydri- 
odic  (HI),  and  hydrofluoric  (HF). 

Combinations  of  it  with  nitrogen  and  oxygen  are  also 
known  in  the  forms  of  nitrous  acid  (HNO2)  and  nitric  acid 
(HNO3)  ;  and  with  sulphur  and  oxygen  in  the  forms  of 
sulphurous  and  sulphuric  acids  (H2SO3  and  H2SO4). 

It  forms  a  constituent  part  of  all  hydrocarbons — that  is, 
combinations  of  hydrogen  with  carbon,  and  with  carbon  and 
nitrogen  it  forms  hydrocyanic  acid  (HCN). 

With  sulphur  alone,  it  forms  the  compound  hydrogen 
sulphide  (H2S),  and  is  a  constituent  of  innumerable 
organic  compounds. 

With  nitrogen  alone,  it  exists  in  combination  as  am- 
monia (NH3),  and  it  forms  so-called  hydrides  with  many 
metals,  such  as  arsenic  and  antimony,  the  arsenical  com- 
pound being  what  is  otherwise  known  as  arseniuretted 
hydrogen  (AsH3). 

HYDROGEN  CHLORIDE— See  Chlorine. 

HYDROGEN  DIOXIDE  or  PEROXIDE  OF  HYDROGEN  (H2O2) 
is  a  very  interesting  substance  nearly  related  to  water,  and 
differing  therefrom,  in  that  its  molecule  contains  i  atom 


254  HYDROGEN  DIOXIDE 

HYDROGEN  DIOXIDE  (Continued)— 

more  oxygen.  It  can  be  prepared  in  a  number  of  ways, 
one  of  which  consists  in  mixing  barium  peroxide  (BaO2) 
with  dilute  sulphuric  acid,  when  the  following  interaction 
takes  place  : 

H2O2. 


Another  method  consists  in  treating  barium  peroxide  in 
the  presence  of  water  with  carbon  dioxide  under  pressure. 
The  dilute  solution  of  hydrogen  dioxide  thus  resulting,  can 
be  concentrated  to  some  extent  by  evaporation,  or  it  can  be 
purified  by  distilling  at  a  low  pressure  and  concentrated  up 
to  90  per  cent,  by  an  appliance  known  as  the  "  sulphuric 
acid  concentrator,"  and  from  this  solution  100  per  cent. 
peroxide  can  be  obtained  by  fractional  freezing. 

The  pure  peroxide  is  quite  stable  if  kept  at  o°  C.  ;  its 
freezing  point  is  —  1-7°  C.,  and  its  sp.  gr.  at  o°  C.  is  i'4633. 
As  ordinarily  prepared,  it  is  often  unstable  and  apt  to  de- 
compose with  explosive  violence. 

There  is  also  a  process  for  making  this  compound  by 
electrolyzing  sulphuric  acid  (using  a  platinum  anode),  and 
the  subsequent  conversion  of  the  persulphuric  acid  thus 
produced  into  hydrogen  dioxide.  It  is  stated  that  sodium 
persulphate  can  be  produced  to  a  greater  degree  of  concen- 
tration than  the  free  acid,  and  that  distillation  of  the  once 
recrystallized  sodium  salt  gives  reasonably  high  yields  of 
the  peroxide. 

It  is  always  found  amongst  the  products  which  result 
when  phosphorus  or  turpentine,  and  terpenes  generally, 
are  exposed  to  air  and  moisture.  It  also  occurs  in  nature, 
being  found  present  in  the  air  following  lightning  discharges 
and  under  some  other  circumstances. 

Hydrogen  dioxide  readily  parts  with  its  second  atom  of 
oxygen  and  is  a  very  valuable  sanitary  and  oxidizing  agent, 
being  one  of  the  constituents  of  the  disinfecting  fluid  known 
commercially  as  "Sanitas"  Fluid.  Solutions  of  it  in  water 
are  largely  used  for  bleaching  straw,  hair,  and  other 
articles,  also  in  the  practice  of  surgery,  on  account  of  its 
antiseptic  character  and  its  power  to  destroy  septic  matter 
in  wounds  by  oxidation.  It  is  odourless  and  colourless 
like  water,  to  which  substance  it  is  reduced  when  it  parts 
with  its  active  oxygen  : 


It,  is   soluble   in   alcohol,   and    a  dilute   solution   of  it 
in  water  can  be  used  to  restore  oil-paintings  which  have 


HYDROGEN  DIOXIDE— HYDROMETER  255 

HYDROGEN  DIOXIDE  (Continued)— 

become  discoloured  owing  to  the  formation  of  lead 
sulphide  (through  exposure  to  the  air  of  towns  containing 
sulphur),  by  reason  of  its  power  of  oxidizing  the  black 
sulphide  into  white  lead  sulphate. 

HYDROGEN  SULPHIDE— See  Sulphur. 
HYDROGENATION  (OF  OILS)— See  Hydrogen. 

HYDROLYSIS — The  splitting  up  of  a  more  or  less  complicted 
substance  into  simpler  or  proximate  bodies  by  the  fixation 
of  water ;  enzymes,  acids,  and  alkaline  hydrates  being  the 
agents  often  employed  for  this  purpose.  The  decomposition 
of  fats  by  the  agency  of  superheated  steam  is  also  an  act  of 
hydrolysis.  (See  Soap,  Amygdalin,  and  Glucosides.) 

HYDROMETER— An  appliance  of  a  simple  character  for 
determining  the  approximate  specific  gravity  of  liquids. 
It  consists  of  a  graduated  glass  tube, 
A,  swelling  to  a  globe  of  glass,  B, 
counterpoised  by  an  adjusted  weight  which 
often  takes  the  form  of  a  small  quantity 
of  mercury  imprisoned  in  the  smaller 
bulb,  C.  When  placed  in  any  liquid 
contained  in  a  cylinder  sufficiently  deep 
(as  shown  in  figure),  it  sinks  until  it  has 
displaced  a  volume  of  the  liquid  equal  to  its 
own  weight.  In  a  heavy  liquid  it  will  sink 
to  a  smaller  extent  than  in  a  lighter  liquid. 
They  are  made  of  several  types — i.e.,  for 
liquids  lighter  than  water  and  for  those  which 
are  heavier  ;  but  in  both  cases  they  are  constructed  so  that 
a  part  of  the  graduated  stem  floats  above  the  surface  of  the 
liquid,  the  density  of  which  is  to  be  determined.  Sikes's 
hydrometer  for  ascertaining  the  alcoholic  strength  of 
spirituous  liquors  is  constructed  on  this  principle,  and  there 
are  tables  made  out  so  that  the  graduations  on  the  stem 
correspond  to  definite  percentages  of  alcohol,  water  being 
marked  as  zero  or  the  standard.  "Proof  spirit"  consists  of 
5072  parts  water  and  40/28  parts  alcohol  by  weight,  and 
indicates  alcohol  of  sp.  gr.  0-920  at  60°  F.  (15-56°  C.). 

It  is  important  in  determining  densities  by  means  of  the 
hydrometer  to  pay  great  attention  to  the  temperature,  as 
small  differences  in  that  respect  make  considerable  varia- 
tions in  the  result.  It  is  usual  to  observe  at  a  tempera- 
ture of  60°  F.  or  15-56°  C.,  at  which  temperature  the  hydro- 
meter is  graduated. 


HYDROMETER 


HYDROMETER  (Continued)— 

SPECIFIC  GRAVITIES  (DENSITIES)  ON   BAUME'S  HYDROMETER 
FOR  LIQUIDS  LIGHTER  THAN  WATER  AT  60°  F.  OR  15*56°  C. 


Degrees. 

Sp.  Gr. 

Degrees. 

Sp.  Gr. 

Degrees. 

Sp.  Gr. 

Degrees. 

Sp.  Gr. 

10 

I  '0000 

26 

0-8974 

41 

0-8187 

56 

0-7527 

II 

0-9929 

27 

0-8917 

42 

0-8140 

57 

0-7487 

12 

0-9859 

28 

0-8861 

43 

0-8092 

58 

0-7447 

I3 

0-9790 

29 

0-8805 

44 

0-8046 

59 

07407 

J4 

0-9722 

30 

0-8750 

45 

0-8000 

60 

0-7368 

15 

0-9655 

31 

0-8696 

46 

07955 

61 

0-7330 

16 

0-9589 

32 

0-8642 

47 

0-7910 

62 

0-7292 

I7 

0-9524 

33 

0-8589 

48 

0-7865 

63 

0-7254 

18 

0<9459 

34 

0-8537 

49 

0-7821 

64 

0-7216 

19 

0-9396 

35 

0-8485 

5° 

0-7778 

65 

07179 

20 

G'9333 

36 

0-8434 

5i 

07735 

66 

0-7143 

21 

0-9272 

37 

0-8383 

52 

0*7692 

67 

07107 

22 

0-9211 

38 

0-8333 

53 

0*7650 

68 

0-7071 

23 

0-9150 

39 

0-8284 

54 

0*7609 

69 

07035 

24 

0-9091 

40 

0-8235 

55 

0-7568 

70 

0-7000 

25          0-9032 

The  degrees  of  TwaddelFs  hydrometer  are  convertible 
into  corresponding  specific  gravities  by  multiplying  them  by 
0-005  and  adding  rooo. 

DEGREES    ON    TWADDELL'S    HYDROMETER,    AND    THE 
CORRESPONDING  DENSITIES  AT  60°  F.  OR  15-56°  C. 


Degrees. 

Sp.  Gr. 

Degrees. 

Sp.  Gr. 

Degrees. 

Sp.  Gr. 

Degrees. 

Sp.  Gr. 

I 

1-005 

II 

•055 

21 

I-I05 

31 

•155 

2 

•oio 

12 

•060 

22 

I-IIO 

32 

•160 

3 

•015 

13 

•065 

23 

I-II5 

33 

•165 

4 

•O2O 

*4 

•070 

24 

I-I2O 

34 

•170 

5 

•025 

15 

•075 

25 

I*I25 

35 

**75 

6 

•030 

16 

•080 

26 

I-I30 

36 

•180 

7 

•035 

i7 

•085 

27 

I-I35 

37 

•185 

8 

•040 

18 

•090 

28 

I-I40 

38 

•190 

9 

•045 

19 

•095 

29 

IBI4S 

39 

i'i95 

10 

•050 

20 

i-ioo 

30 

1-150 

40 

i  -200 

HYDROMETER—"  HYDROSOL  "  257 

HYDROMETER  (Continued)— 

SPECIFIC  GRAVITIES  (DENSITIES)  CORRESPONDING  TO 

DEGREES  OF  BAUME'S  HYDROMETER  FOR  LIQUIDS 

HEAVIER  THAN  WATER  AT  60°  F.  OR  15*56°  C. 


Degrees 

Sp.  Gr. 

Degrees. 

Sp.  Gr. 

Degrees. 

Sp.  Gr. 

Degrees 

Sp.  Gr. 

0 

I  -OOOO 

18 

1-1417 

36 

1-3303 

54 

1-5934 

I 

1*0069 

19 

1-1508 

37 

1-3426 

55 

1-6111 

2 

1-0140 

20 

•1600 

38 

I-355I 

56 

1-6292 

3 

I  -O2  1  1 

21 

•1694 

39 

1-3679 

57 

1-6477 

4 

1-0284 

22 

•1789 

40 

1-3810 

58 

1-6667 

5 

I<0357 

23 

•1885 

4i 

1-3942 

59 

1-6860 

6 

1-0432 

24 

•1983 

42 

1-4078 

60 

1-7059 

7 

1-0507 

25 

•2083 

43 

1-4216 

61 

1-7262 

8 

1-0584 

26 

•2185 

44 

I-4356 

62 

1-7470 

9 

1-0662 

27 

•2288 

45 

1-4500 

63 

1-7683 

10 

1-0741 

28 

1-2393 

46 

I  -4646 

64 

1-7901 

ii 

1-0821 

29 

1-2500 

47 

1-4796 

65 

1-8125 

12 

1-0902 

30 

1-2609 

48 

1-4948 

66 

I-8354 

I3 

1-0985 

31 

1-2719 

49 

1-5104 

67 

1-8590 

J4 

1-1069 

32 

1-2832 

50 

1-5263 

68 

1-8831 

15 

I'II54 

33 

1-2946 

5i 

1-5426 

69 

1-9079 

16 

1-1240 

34 

1-3063 

52 

I'559I 

70 

1*9333 

17 

1-1328 

35 

1-3182 

53 

1-5761 

HYDRO-EXTRACTORS — See  Centrifuges. 

HYDROQUINONE  or  QUINOL  (Dihydroxybenzene)  (C6H4(OH)2) 
— A  white,  crystalline  compound  used  as  a  developer  in 
photography  on  account  of  its  strong  reducing  action.  It 
melts  at  169°  C.  and  can  be  obtained  by  the  hydrolysis  of 
the  glucoside  named  arbutin,  or  by  the  oxidation  of  quinic 
acid  (C7H12O6)  with  lead  dioxide,  etc.  It  is  soluble  in 
water,  alcohol,  and  ether. 

"  HYDROS  "—An  abbreviated  name  for  hydrosulphite  of 
sodium,  used  as  a  decolourizing  agent,  by  removal  of 
iron  compounds  from  soap  after  the  process  of  saponifi- 
cation  is  completed  (2  to  3  Ib.  being  used  for  every  1,000 
Ib.  of  fats). 

"EYDROSOIi"— See  Colloid, 


258  HYDROSULPHIDES—HYPOCHLORITES 

HYDROSULPHIDES  (Sulphydrates)  —  If  potassium  be  heated 
in  hydrogen  sulphide  gas  potassium  hydrosulphide  is  formed, 
hydrogen  being  at  the  same  time  set  free  — 


and  the  same  substance  is  produced  in  solution,  by  passing 
a  current  of  hydrogen  sulphide  into  a  solution  of  potassium 
sulphide  — 

=  2KHS. 


Hydrosulphides  of  the  alkalies  and  alkaline  earths  are  also 
termed  sulphydrates. 

Sodium  hydrosulphide  (NaHS.2H2O)  can  be  obtained  in 
the  form  of  colourless  needles,  soluble  in  water,  by  treating 
calcium  sulphide  with  sodium  bisulphate. 

HYDROXIDES—  See  Bases. 

HYDROXYL  (HO)  —  A  monad  radical  group  which  exists  in 
many  chemical  combinations,  such  as  hydroxylamine  —  that 
is,  ammonia  (NH3)  in  which  one  of  the  hydrogen  atoms 
is  replaced  by  the  group  HO,  becoming  NH2(OH).  (See 
Oximes.) 

Again,  ethyl  alcohol  (C2H6O)  may  be  regarded  as  con- 
stituted of  the  radicals  C2H5  and  HO  (C2H6HO). 

HYGROMETERS—  Special  varieties  are  made  for  determining 
the  humidity  of  the  air  in  timber,  leather,  and  paper-drying 
rooms,  etc.  (See  Air,  p.  9.) 

HYGROSCOPIC—  The  property  of  absorbing  moisture  from 
the  air.  This  is  not  limited  to  solids  ;  sea  water,  for 
example,  is  capable  of  absorbing  moisture  from  the  air 
when  saturated  with  it,  at  the  same  temperature. 

HYOSCIME—  See  Henbane. 
HYOSCYAMINE—  See  Henbane. 

HYPO  as  a  prefix  in  chemical  nomenclature  is  used  to  dis- 
tinguish a  compound  from  other  members  of  a  series,  as, 
for  example,  nitrous  and  nitric  acid  —  the  term  hyponitrous 
acid  indicating  the  acid  containing  the  least  oxygen. 

HNO2  is  nitrous  acid,  HNO3  is  nitric  acid,  and  H2N2O2 
is  hyponitrous  acid. 

"HYPO"  —  This  term  is  also  used  as  a  common  name  for 
sodium  thiosulphite  (hyposulphite)  of  sodium. 

HYPOCHLORITES—  Salts  of  hypochlorous  acid.  (See  Chlorine,) 


HYPOCHLOROUS  ACID—  IMPERMEABLE  259 

HYPOCHLOROUS  ACID  —  See  Chlorine. 
HYPOPHOSPHOROUS  ACID—  See  Phosphorus. 
HYPOSULPHITE  OF  SODIUM—  See  Sodium. 
HYPOSULPHUROUS  ACID—  See  Sulphur. 

HYPOTHESIS  —  A  conjectural  or  speculative  view  of  matters 
not  in  opposition  to  ascertained  facts. 

HYSSOP  OIL—  A  colourless  essential  oil  distilled  from  the 
herb  Hyssopus  officinalis.  It  is  soluble  in  alcohol  and  ether, 
has  a  sp.  gr.  of  0*932,  and  is  used  in  medicine,  etc. 

ICE  —  See  Water  ;  also  footnote  in  Heat  section  (p.  240). 

ICELAND  MOSS  —  A  lichen  (Cetraria  islandica)  containing  a 
mucilage  which  can  be  extracted  by  hot  water. 

ICELAND  SPAR  (Calcite  —  Transparent  Calcspar)—  A  mineral 
form  of  calcium  carbonate. 

ICHTHYOCOLL—  See  Isinglass. 

ICHTHYOL  —  An  indefinite  chemical  mixture  of  sulphonated 
hydrocarbons  obtained  by  the  dry  distillation  of  certain 
bituminous  shales  ;  used  in  medicine. 

IGNITION  —  Setting  on  fire  or  taking  light.  A  piece  of  paper 
ignites  on  applying  a  lighted  match.  A  jet  of  coal  gas  takes 
light  in  the  same  way,  and  both  the  paper  and  gas  are  thus 
ignited  and  burn  with  production  of  light  and  heat.  The 
temperature  at  which  combustion  of  a  substance  takes 
place  is  known  as  its  ignition-point.  It  is  not  always 
necessary  to  apply  a  light  to  cause  combustion  ;  phosphorus 
takes  fire  on  exposure  to  the  air,  and  if  sodium  be  warmed 
in  the  air  it  also  will  burn,  forming  the  peroxide 


ILANG-ILANG  OIL—  See  Ylang-ylang. 

ILMENITE  —  A  mineral  compound  of  iron  and  titanium  oxides. 

IMIDES  —  Anhydrides  of  certain  acids  in  which  the  oxygen 
atom  is  replaced  by  the  imido-group  (NH)  —  for  example, 
succinimide  (C,H4(CO)2NH),  a  crystalline  substance  formed 
by  heating  ammonium  hydrogen  succinate. 

IMPERMEAELE  —  Fabrics  rendered  waterproof  by  various 
processes  are  described  as  impermeable.  Bathstone  sur- 
faces can  be  rendered  more  or  less  impermeable  by  washing 
over  with  sodium  silicate,  and  varnishes  give  impermeability 
to  the  surfaces  of  various  articles. 


260  IMPER  VIO  US— INDIGO 

IMPEEVIOUS — Not  admitting  passage. 

INCANDESCENT  —  A  state  of  heat  at  which  a  substance 
begins  to  give  out  light  or  to  glow.  The  wires  of  electric 
lamps  and  the  mantles  used  for  intensifying  gas  flames  are 
incandescent  when  in  use. 

INCINERATION — The  process  of  reduction  to  ashes  by  burn- 
ing or  ignition. 

INDIAN  INK  (Chinese  Ink)— See  Inks. 

"INDIAN  OIL" — A  proprietary  quick-drying  white  spirit 
distilled  from  crude  mineral  oil,  of  sp.  gr.  800,  and  with 
closed  flash-point  over  80°  F.,  advocated  as  a  solvent  and 
turpentine  substitute. 

INDIAN  RED — A  natural  pigment  from  the  Persian  Gulf, 
containing  ferric  silicate  (Fe2O3SiO2). 

INDIA-RUBBER  (Caoutchouc)— See  Rubber. 

INDICAN  (C26H31NO1?)— The  active  principle  of  the  indigo 
plant,  from  which  indigo  blue  is  obtained.  It  is  of  the 
character  of  a  glucoside,  and  is  resolved  by  hydro- 
lysis into  indigo  blue  and  a  glucose-like  body  named 
indiglucin : 

2C2eH   N017  +  4H20  =  C18H10N202  +  6C8HIOO6. 

(Indican.)  (Indigo  blue        (Indiglucin.) 

or  Indigotin.) 

In  the  pure  state,  indican  is  a  colourless  substance,  but 
by  treatment  with  acids  or  by  the  action  of  enzymes  it  is 
split  up  as  shown  by  the  above  equation  and  yields  indigo 
blue  (indigotin),  which  can  be  obtained  as  a  dark  blue, 
crystalline  powder  which  sublimes  at  300°  C.  and  is  soluble 
in  aniline,  chloroform,  glacial  acetic  acid,  and  strong  sul- 
phuric acid. 

INDICATORS — See  Volumetric  Analysis. 

INDIGO — A  blue  colouring  matter  prepared  from  the  plant 
Indigofera  tinctovia  and  formed  from  indican,  which  exists  in 
its  juice  and  that  of  some  other  plants,  including  the 
West  African  plant  Louchocarpus  cyanescens.  (See  Woad.) 
Well-made  samples  are  said  to  contain  70  per  cent,  of  the 
specific  compound  indigotin  (C16H1.N2O2)  associated  with 
other  substances  which  have  an  influence  in  the  dye-vat, 
and  which  probably  accounts  for  the  superiority  of  natural 
indigo  over  manufactured  indigotin,  which  is  now  made 
synthetically  from  naphthalene  or  phthalic  acid. 


INDIGO  261 

INDIGO  (Continued)— 

The  synthetic  production  of  indigo  starts  with  naphtha- 
lene, which  is  first  of  all  oxidized  to  phthalic  acid,  and  this 
by  sublimation  is  converted  into  phthalic  anhydride 
(C6H4(CO)2O)  which  when  heated  in  presence  of  ammonia 
yields  phthalimide  (C6H4(CO)2NH)  and  this  compound 
when  subjected  to  the  action  of  alkalies  and  an  alkaline 
hypochlorite  produces  anthranilic  acid  (CgHj.NHg.COgH). 

By  interaction  with  monochloracetic  acid,  anthranilic 
acid  gives  phenyl-glycine-ortho-carboxylic  acid,  and  this 
when  melted  with  an  alkali  and  made  into  solution  is 
oxidized  by  a  current  of  air,  thereby  producing  indigo  blue. 

Another  process  consists  in  treating  aniline  with 
chloracetic  acid,  thus  producing  the  phenyl-glycine 
(C6H5.NH.CH2.COOH),  which  when  heated  with  soda- 
mide  (NH2Na),  or  metallic  sodium  in  the  presence  of 
ammonia,  yields  indigo  blue  through  oxidation  of  the  inter- 
mediate compound  named  indoxyl  (C6H4NH.CO.CH2). 

The  Indian  cultivation  of  indigo  has  fallen  off  very  much  in 
recent  years  on  account  of  its  synthetic  production.  Even 
so  late  as  1918-19  the  acreage  under  production,  which  had 
exceeded  one  and  a  half  million  acres  in  1896-7,  was  less  by 
59  per  cent,  than  in  the  previous  year,  280,000  acres  only 
being  under  growth,  and  yielding  about  32,100  cwt. ; 
although  it  has  been  stated  that  the  acreage  under  culti- 
vation in  1916-17  had  risen  to  750,000  acres  and  produced 
nearly  5,000  tons  of  indigo. 

The  indigo  plant  is  cultivated  in  Southern  Nigeria  and 
yields  indigo  containing  56  per  cent,  indigotin  when  treated 
as  in  India. 

Indigo  is  insoluble  in  water,  but  soluble  in  aniline, 
nitro-benzene,  and  chloroform,  and  dissolves  in  hot  strong 
sulphuric  acid  to  a  deep  blue  colour ;  it  is  this  solution 
of  indigo-sulphuric  acid  that  is  used  in  dyeing. 

Indigo  Blue  is  prepared  by  cutting  the  plants  just  before 
flowering  and  steeping  in  water,  when  a  fermentation  takes 
place,  yielding  a  yellow-coloured  liquor  which  is  drawn  off 
after  some  twelve  to  fifteen  hours  and  subsequently  agitated 
in  contact  with  the  air,  in  which  process  oxygen  is  absorbed 
and  the  indigo  is  thrown  down  as  a  greenish-blue  precipitate. 
This  is  strained  off,  pressed,  dried,  and  cut  up  into  the  cakes 
of  commerce. 

The  same  colouring  matter  is  also  yielded  by  woad 
(Isatis  tinctovia). 

A  considerable  amount  of  indigo  is  now  produced  in 
Manchuria.  (See  Indican  and  Indigo  White.) 


262  INDIGO— INKS 

INDIGO  (Continued)—  • 

Indigo  White  (Ci6H12N2O2)  is  a  white,  crystalline  powder 
obtained  from  indigo  by  a  process  of  reduction,  and  it  is 
used  in  dyeing,  by  making  use  of  processes  which  are 
capable  of  reconverting  it  into  indigo  blue  on  contact  with 
the  fabrics. 

Indigo  Carmine,  or  soluble  indigo,  prepared  by  treating  a 
sulphuric  acid  solution  of  indigo  with  soda.  It  is  a  blue 
powder  soluble  in  water  and  used  in  dyeing. 

INDIUM  (In) — Atomic  weight,  114*8;  sp.  gr.,  about  7-1  ;  melt- 
ing-point, 176°  C.  A  rare  element  so  named  on  account 
of  the  two  lines  it  exhibits  in  the  indigo-blue  part  of  the 
spectrum.  It  is  supposed  to  be  analogous  to  aluminium 
and  occurs  in  many  zinc-blendes.  It  is  a  ductile,  soft, 
silver-white  metal,  and  its  compounds  give  a  violet  tinge 
to  the  Bunsen  flame.  It  is  easily  soluble  in  acids,  and 
forms  alloys  with  lead  and  thallium.  There  are  two  oxides 
(InO  and  In2O3);  a  hydroxide  (In(OH)3)  ;  two  chlorides 
(InCland  InCl2) ;  a  bromide  (InBr3);  iodide  (InI3) ;  nitrate 
(In(NO3)6,9H2O) ;  sulphate  (In(SO4)3),  etc.  The  metal 
resembles  aluminium  in  forming  alums  and  the  halogen 
salts  are  soluble  in  water. 

INDUCTION — The  power  exhibited  by  a  body  of  inducing  a 
corresponding  state  in  another  body,  as  when  a  rotating 
magnet  acts  in  the  dynamo.  (See  Electricity.) 

INFUSION — An  extract  prepared  by  steeping  or  digesting  a 
substance  or  parts  of  plants  in  a  solvent  liquid. 

INFUSORIAL  EARTH — A  light-coloured  siliceous  deposit 
found  near  Ebsdorf,  also  in  the  United  States  and  else- 
where, is  known  by  this  name,  but  it  is  also  applied  to 
other  deposits  such  as  kieselgiihr  and  atomite. 

INHALATION — The  act  of  inhaling  or  breathing  in  through 
the  mouth  and  nose. 

INKS — Liquids  or  pigments  used  for  writing  or  printing,  those 
for  writing  being  made  of  various  colours — black,  blue, 
green,  and  red. 

Black  Ink  is  a  mixture  of  an  infusion  of  gall  nuts  with 
ferrous  sulphate,  and  a  certain  proportion  of  gum  arabic 
dissolved  in  the  mixture  to  give  body  and  gloss  to  the  ink. 
Sometimes  logwood  and  indigo  carmine  are  added,  and 
there  are  many  recipes  for  its  preparation. 

Blue  Ink  can  be  prepared  by  dissolving  Prussian  blue  in 
a  dilute  solution  of  oxalic  acid. 


INKS—INORGA  NIC  263 

INKS  (Continue^— 

Red  Inks  are  prepared  from  cochineal  or  Brazil-wood,  or 
by  dissolving  carmine  in  ammonia  solution. 

Indelible  Ink  is  prepared,  amongst  other  methods,  by 
mixing  ordinary  ink  with  Indian  ink  or  lamp-black  rubbed 
up  with  weak  hydrochloric  acid. 

Copying  Ink  is  prepared  from  logwood  extract  dissolved 
in  vinegar  and  water,  to  which  certain  quantities  of  copper 
sulphate,  alum,  gum,  and  sugar  are  added. 

The  formula  adopted  by  the  United  States  Government 
is  as  follows  : 

Tannic  acid  ...  ...  ...  46*8  grammes 

Gallic  acid  ...  ...  .,  15-4  „ 

Ferrous  sulphate  ...  ...  ...  60*0  ,, 

Gum  arabic  ...  ...  ...  10*0  „ 

Dilute  hydrochloric  acid  (U.S. P.)      ...  50-0  „ 

Phenol     ...  ...  ...  ...  i'o  „ 

Suitable  blue  dye  ...  ...  ...  4-4  „ 

and  water  to  make  up  to  1,000  c.c.  at  15*6°  C. 

Cancelling  Inks  must  contain  pigment  and  dyes  of  such 
character  as  to  penetrate  the  fibre  of  paper  so  that  the 
mark  cannot  be  removed.  They  vary  in  composition,  but 
lamp-black  is  often  used  in  conjunction  with  a  coal-tar  dye 
and  some  non-drying  oil. 

Sympathetic  Inks  are  variously  prepared,  cobalt  salts 
being  used  for  some  makes.  (See  Cobalt.) 

Marking  Ink  usually  consists  of  silver  nitrate  solution 
coloured  and  thickened  with  gum,  but  many  others  consist 
of  cresol  and  dye. 

Printing  Inks  are  made  in  great  variety,  but  consist  in 
the  main  of  lamp-black  mixed  with  linseed  oil ;  soap  and 
rosin  being  sometimes  incorporated. 

Chinese  Ink  is  made  from  vegetable  charcoal  prepared 
from  rice  straw  or  vegetable  oils,  and  suitable  materials. 

Indian  Ink  is  a  black  powder  imported  from  China,  said 
to  be  made  from  carbon  prepared  by  burning  camphor, 
cemented  with  gelatine  or  glue. 

Invisible  Ink — See  Cobalt,  p.  126. 

INORGANIC — This  term  is  applied  to  all  substances  that 
do  not  contain  carbon  as  a  constituent,  also  to  some  few 
others  in  which  carbon  is  present  in  an  unimportant 
sense.  The  natural  rocks  and  earths,  the  metals  and 


264  INORGANIC— INULIN 

INORGANIC  (Continued)— 

minerals,  are  all  inorganic  bodies.  Such  substances  as 
the  metallic  carbonates  are  regarded  as  inorganic  for  the 
reason  above  given.  (See  Carbon.) 

INOSITE  (Inositol)— (C6H12O6)2H2O— A  crystalline  sugar-like 
substance  found  in  the  muscles  of  the  heart  and  in  certain 
other  animal  tissues.  It  loses  its  water  of  crystallization  at 
1 00°  C.,  and  is  not  susceptible  to  alcoholic  fermentation. 

INSECT  POWDER  (Pyrethrnm  Powder) — The  dried  unexpanded 
heads  of  Chrysanthemum  cineraria  folium,  of  which  the  ground 
Montenegrin  or  Dalmatian  variety  is  the  best,  its  insecticidal 
properties  being  due  to  its  constituent  pyrethrotoxic  acid. 

INSOLUBLE — Incapable  of  being  dissolved.  Sand,  for  instance, 
is  insoluble  in  alcohol,  and  all  the  metals  are  insoluble  in 
water. 

INSULATION — Detachment  or  placing  out  of  communica- 
tion. Electric  cables  are  insulated  with  a  covering  of 
gutta-percha  to  prevent  the  leakage  of  the  electric  current 
by  conductivity. 

INTERACTIONS— See  Chemical  Interactions. 

INTERMEDIATES — A  general  term  for  a  great  number  of 
complex  derivatives  obtained  by  chemical  processes  from 
anthracene,  benzene,  cresols,  naphthalene,  phenol,  toluene, 
and  other  direct  coal-tar  products,  all  of  which  are  used  in 
the  manufacture  of  synthetic  dyes. 

They  include  aniline  oil,  naphthol  (alpha  and  beta), 
naphthalene,  naphthylamines,  phthalic  anhydride,  anthran- 
ilic  acid,  dimethylaniline,  nitro-benzene,  paranitraniline, 
resorcin,  salicylic  acid,  and  many  other  compounds,  some 
of  which  are  described  under  their  respective  names. 

INULIN  or  ALANT  STARCH  (C9H10O6)><— A  carbohydrate 
contained  in  dahlia  bulbs  (Dahlia  variabilis)  to  the  extent  of 
about  10  per  cent,  of  the  weight  of  the  ripe  tubers,  and  in 
smaller  proportions  in  the  roots  of  other  members  of  the 
Composite,  such  as  chicory  and  artichokes.  In  the  pure 
state  it  is  a  white  powder  resembling  starch,  but,  unlike  that 
substance,  it  dissolves  in  aqueous  sodium  hydroxide  and  in 
hot  water  to  a  clear  solution,  and  is  not  coloured  blue  by 
iodine.  It  is  unaffected  by  diastase,  and  is  not  fermentable 
by  yeast,  but  when  boiled  with  water  or  dilute  acid  it  is 
converted  into  a  variety  of  fructose.  It  is  used  in  the  pre- 
paration of  diabetic  bread,  and  is  a  stronger  sweetener  than 
cane  sugar. 


IN  VERT  A  SE— IODINE  265 

INVERTASE  (Invertin) — An  enzyme  present  in  ordinary  yeast 
which,  apart  from  the  yeast  cells  themselves,  has  the  power 
of  converting  (inverting)  cane  sugar  into  glucose  and  fruc- 
tose by  hydrolysis,  to  the  reported  extent  of  200,000  times 
its  own  weight  of  cane  sugar  without  then  losing  its  effect — 

C12H22On  +  H20  =  C6H1206  +  C6H1206. 

The  product  is  known  as  "  invert  sugar,"  and  whereas  a 
solution  of  cane  sugar  is  dextro-rotatory,  the  hydrolyzed 
product  is  lasvo-rotatory,  the  fructose  being  more  strongly 
laevo-rotatory  than  the  glucose  is  dextro-rotatory. 

INVERT  SUGAR— See  Invertase. 
IODATES— See  Iodine. 
IODEOSIN — See  Volumetric  Analysis. 
IODIC  ACID— See  Iodine. 
IODIDES— See  Iodine. 

IODINE  (I)— Atomic  weight,  127;  sp.  gr.,  4-95;  melting- 
point,  113*5°  C.  Iodine  is  widely  distributed  in  nature, 
being  found  in  compound  form  (only)  associated  with 
potassium,  sodium,  magnesium,  and  calcium.  It  is  also 
present  in  sea  water,  seaweeds,  and  caliche  or  Chili  saltpetre 
(sodium  nitrate).  It  is  prepared  to  some  extent  from  kelp 
(ashes  from  seaweed),  but  chiefly  from  the  mother-liquor 
of  the  Chili  saltpetre  above  named,  which  contains  less 
than  J  per  cent.,  and  that  of  the  Stassfurt  salt  deposits. 

The  seaweeds  which  contain  most  iodine  are  of  the  so- 
called  "  drift"  order — viz.,  Laminaria  digitata  and  Laminaria 
stenophylla,  each  of  which  contains  a  little  less  than  \  per  cent. 
The  ash  of  the  roots  of  L.  hyperborea  contains  about  i  per 
cent.,  the  stalks  about  3  per  cent.,  and  that  of  the  leaves 
about  4  per  cent,  iodine. 

Iodine  is  a  blue-black,  shining  substance,  easily  obtained 
in  crystalline  form,  which  readily  vapourizes,  the  vapour 
having  a  beautiful  violet  colour.  It  has  a  characteristic 
penetrating  odour  and  is  only  slightly  soluble  in  water, 
but  readily  soluble  in  a  solution  of  potassium  iodide, 
alcohol,  carbon  disulphide,  chloroform,  ether,  etc.  Even 
an  extremely  dilute  solution  of  iodine  gives  with  starch 
solution  an  intensely  blue-coloured  compound. 

In  general  properties  it  strongly  resembles  its  family 
neighbours  chlorine  and  bromine.  Dilute  solutions  of  it 
in  water  and  alcohol  are  used  in  surgery  as  antiseptics. 


266  IODINE— IODINE  VALUE 

IODINE  (Continued)— 

Iodine  in  combination  with  the  alkaline  metals  forms 
iodides,  the  most  valuable  of  which  is  potassium  iodide 
(KI),  which  is  produced  in  solution  together  with  potas- 
sium iodate,  when  iodine  is  dissolved  in  a  warm  solution 
of  potassium  hydrate.  It  crystallizes  in  anhydrous  cubes, 
is  very  soluble  in  water,  and  is  extensively  employed  as  a 
medicament. 

Hydriodic  Acid  (HI)  can  be  prepared  in  a  variety  of 
ways,  but  most  readily  by  the  action  of  phosphorus  upon 
iodine  in  presence  of  water,  thus  giving  rise  to  production 
of  the  HI  gas,  which  is  colourless,  pungent,  and  extremely 
soluble  in  water,  a  saturated  solution  having  a  sp.  gr.  of  1*67 
at  the  ordinary  temperature  and  pressure. 

lodic  Acid  (HIO3)  is  a  crystalline,  white,  solid  body, 
soluble  in  water,  and  forms  iodates  such  as  potassium 
iodate  (KIO3)  corresponding  to  potassium  chlorate  (KC1O3). 

Iodine  Pentoxide  (I2O5)  is  a  white,  crystalline  body, 
soluble  in  water,  which,  when  heated  to  300°  C.,  is  split 
up  into  iodine  and  oxygen. 

Iodine  forms  two  compounds  with  chlorine — viz.,  iodine 
monochloride  (IC1)  and  trichloride  (IC13).  Both  these 
compounds  are  formed  by  passing  dry  chlorine  gas  over 
iodine,  when  it  first  of  all  melts  to  a  dark  reddish-brown 
colour  and  subsequently  solidifies  to  a  mass  of  red  crystals 
of  IC1  if  care  be  taken  not  to  use  an  excess  of  chlorine, 
but  if  more  chlorine  be  used,  then  the  yellow  trichloride  in 
crystalline  form  is  produced. 

Iodine  Cyanide  (ICN)  is  a  colourless,  crystalline  sub- 
stance of  pungent  odour,  and  soluble  in  water,  alcohol,  and 
ether ;  used  as  a  preservative  by  taxidermists. 

Periodic  Acid  (HIO4,2H2O)  is  a  white,  crystalline  body, 
soluble  in  water,  and  having  a  melting-point  of  about 
131°  C.  The  periodates  constitute  a  large  class  of  salts. 

IODINE  VALUE  (of  Oils  and  Fats). — This  determination,  as 
commonly  performed  on  samples  of  oils,  fats,  and  waxes,  is 
used  to  indicate  the  degree  of  unsaturation  of  the  compound 
— that  is,  the  number  of  pairs  of  carbon  atoms  in  which  two 
(or,  in  some  cases,  three)  valency  bonds  are  concentrated 
between  the  two  carbon  atoms. 

Any  such  double  (or  treble)  linkage  is  in  a  state  of 
strain,  and  when  the  substance  containing  it  comes  in 
contact  with  certain  other  substances  (e.g.  the  halogens), 
one  of  the  bonds  breaks  and  two  atoms  of  the  new  substance 


IODINE  VALUE— ION  ONE  267 

IODINE  VALUE  (Continued)— 

are  attached,  one  to  each  of  the  carbon  atoms  originally 
joined  by  the  double  linkage. 

Thus  every  two  atoms  of  the  reagent  absorbed  represent 
one  double  linkage  in  the  original  substance. 

The  reagent  used  in  the  Hubl  or  Wij  method  is  iodine 
monochloride  (IC1),  which  adds  on  one  atom  of  iodine  to  the 
one  carbon  atom,  and  one  atom  of  chlorine  to  the  other. 
Thus  in  this  case,  one  atom  of  iodine  absorbed  indicates  the 
presence  of  one  double  linkage. 

The  method  of  Hubl  is  to  make  up  an  iodine  mono- 
chloride  solution  from  iodine  and  mercuric  chloride,  and 
add  excess  of  this  to  a  known  weight  of  the  substance. 
After  standing  for  some  time,  the  excess  of  iodine  chloride 
is  estimated  by  the  potassium  iodide  and  thiosulphate 
method :  a  blank  test  is  carried  out  alongside,  using  an 
equal  quantity  of  the  reagent  without  the  substance,  and 
the  difference  indicates  the  amount  of  iodine  absorbed  by 
the  substance. 

The  iodine  value  may  be  defined  as  the  amount  of  iodine 
chloride  absorbed  by  100  grms.  of  the  substance,  expressed 
in  terms  of  iodine. 

The  drying  properties  of  oils  are  in  almost  direct  ratio 
of  their  iodine  values.     Saturated  substances  such  as  the 
paraffins  have  iodine  value  nil. 
IODITE — A   Spanish    native    silver    iodide    containing    over 

46  per  cent,  of  silver. 

IODOFORM  (CHI3) — A  yellow,  crystalline  substance  prepared 
by  warming  alcohol  with  iodine  and  alkali,  or  by  heating 
acetone  with  iodine  in  presence  of  an  alkali.  It  melts  at 
120°  C.,  has  a  peculiar  odour  something  like  that  of  saffron, 
and  is  used  as  an  antiseptic  in  the  practice  of  surgery. 
Its  unpleasant  odour  is  removed  by  dissolving  it  in  air- 
oxidized  turpentine,  without  detracting  from  its  value.  It 
is  insoluble  in  water  but  dissolves  in  both  alcohol  and  ether. 

IONISATION— Electrolytic  dissociation.     (See  Electricity.) 

IONIUM— A  substance  possibly  of  an  elemental  character 
obtained  as  a  disintegration  product  from  uranium  minerals, 
giving  a  spectrum  and  exhibiting  chemical  properties 
identical  with  those  of  thorium. 

IONONE— (C13H20O)— An  artificial  essence  of  violet  made 
from  citral  and  acetone.  There  are  several  so-called 
ionones,  one  of  which  is  the  odoriferous  principle  of  the 
iris  root.  (See  Orris  Oil.) 


268  IONS— IRON 

IONS — The  moving  particles  in  an  electrolytic  solution,  one 
set  in  the  direction  of  the  anode  and  the  other  towards  the 
cathode;  those  appearing  at  the  former  are  sty  led  anions  and  the 
positively  charged  ions  are  termed  cations.  (See  Electricity.) 

IPECACUANHA — A  substance  used  as  an  emetic,  prepared 
from  the  dried  root  of  certain  plants  growing  in  South 
America  and  containing  several  active  principles,  including 
"  emetine."  The  best  plant  is  the  Psychotria  ipecacuanha  of 
Brazil  and  New  Granada,  and  the  greater  portion  of  the 
emetine  is  contained  in  the  cortical  part. 

IKIDIUM  (Ir) — Atomic  weight,  193*1  ;  sp.  gr.,  22-4;  melting- 
point,  2,350°  C.  A  white,  hard,  brittle,  and  lustrous  metal, 
occurring  in  alloy  form  with  platinum  in  platinum  ores,  and 
nearly  related  to  that  metal  in  its  chemical  characters. 

The  native  alloy  is  known  as  iridosmine.  It  is  used  in 
alloy  with  platinum  for  hardening,  also  in  making  fountain- 
pen  points.  In  compact  form,  iridium  is  insoluble  in  acids, 
and  it  forms  alloys  with  copper,  gold,  lead,  and  mercury. 
A  number  of  compounds  are  known,  including  three  oxides 
(one  of  which,  known  as  "  iridium  black,"  is  used  as  a 
pigment  for  china  ware),  three  chlorides  (IrCl2,  Ir2Cl6, 
IrCl4),  and  iodides.  Its  salts  are  soluble  in  water,  and,  in 
common  with  palladium,  the  metal  has  the  property  of 
absorbing  gases  by  occlusion.  (See  Occlusion.) 

IRISH  MOSS — Seaweed  (Chondvus  crispus  and  C.  mamillosus) 
containing  nearly  80  per  cent,  of  a  peculiar,  gelatinous 
substance  named  "  caregeenin."  It  finds  some  use  as  a 
food  ;  it  is  also  used  by  dyers  and  calico  printers  for  dress- 
ing the  warp  of  webs,  as  an  agent  for  clarifying  beer,  for 
certain  sizing  purposes,  and  for  leather-dressing. 

IRON  (Ferrum,  Fe)  and  its  Compounds — Atomic  weight,  56 ; 
sp.  gr.,  7*84  ;  melting-point,  1,530°  C.  Iron  occurs  in  nature 
in  the  form  of  many  ores.  Magnetic  iron  ore  (magnetite 
or  loadstone)  (FeO,  Fe2O3)  is  a  compound  of  oxides  of  iron 
from  which  much  of  the  best  Swedish  iron  is  made.  Red 
hamatite  (Fe2O3)  is  largely  mined  in  some  parts  of  Lanca- 
shire, Cumberland,  and  to  some  extent  in  Cornwall,  while 
large  deposits  exist  near  Bilbao  in  Spain  and  elsewhere. 
It  is  greatly  used  in  the  manufacture  of  Bessemer  pig  iron. 
Brown  haematite  (2Fe2O33H2O),  a  hydrated  oxide  of  iron, 
is  the  source  of  much  of  the  iron  made  in  France  and 
Belgium,  whilst  enormous  quantities  of  spathic  ore  or  clay 
ironstone  (which  is  an  impure  carbonate  of  iron  containing 
about  33  per  cent,  of  iron,  and  the  poorest  of  the  iron 


IRON  269 

IRON  (Continued)— 

ores  that  are  worked)  are  used  in  this  country  as  a  source 
of  iron. 

Iron  occurs  naturally  as  carbonate  in  the  forms  of 
blackband  of  the  Scotch  coalfields,  and  in  an  impure  form 
in  the  neighbourhood  of  Northampton. 

Large  deposits  of  micaceous  iron  ore  are  found  in 
Brazil,  whilst  the  Lorraine  district  is  said  to  contain  an 
iron  ore  reserve  of  about  1,800,000,000  tons.  While  in 
German  hands  it  yielded  about  three-fourths  of  their  steel 
output.  It  is  a  brown  haematite  very  rich  in  phosphorus. 

It  has  recently  been  estimated  that  China  possesses,  in 
all,  some  7,000,000,000  tons  of  iron  ore  available  for  treat- 
ment by  native  methods  and  modern  furnaces.  Chromium 
iron  ores  come  largely  from  New  Caledonia,  Rhodesia,  the 
United  States  of  America,  and  Canada. 

Iron  as  manufactured  and  dealt  in  commercially  is  not 
a  pure  metal,  and  varies  very  much  in  composition  and 
qualities  according  to  the  purposes  to  which  it  is  to  be 
applied.  Some  of  the  better-known  kinds  are  named  cast 
iron,  wrought  iron,  foundry  iron,  forge  iron,  steel,  etc.,  and 
their  melting  or  fusing  points  and  other  properties  vary 
with  the  composition. 

Some  21,000,000  tons  of  iron  ore  were  smelted  in  the 
United  Kingdom  in  1916. 

Electro-deposited  Iron  is  employed  in  building  up  worn 
and  other  parts  of  aeroplane  engines,  and  as  a  material  for 
research  work,  being  the  purest  available  form.  It  is  not, 
however,  chemically  pure,  as  it  generally  contains  some 
hydrogen  gas  and  small  proportions  of  carbon,  sulphur, 
silicon,  and  phosphorus. 

Cast  or  Pig  Iron  is  made  in  blast-furnaces  from  mixtures 
of  iron  ore  with  coal  or  coke  and  limestone,  by  which  means 
(the  contents  of  the  furnace  being  maintained  at  a  bright- 
red  heat  by  the  blast  of  air)  the  oxygen  contained  in  the 
oxides  or  other  iron  compounds  is  burned  off  by  the  carbon, 
the  lime  combines  with  the  clayey  part  of  the  ore  and  forms 
the  slag,  leaving  metallic  iron.  The  molten  iron  settles  in 
a  layer  at  the  bottom  of  the  furnace,  the  slag  remaining  on 
its  top.  "  Pig  iron  "  made  in  this  way,  containing  from  2  to  5 
per  cent,  of  carbon  and  small  quantities  of  sulphur,  phos- 
phorus, and  silicon,  is  used  for  making  stoves,  saucepans, 
iron  gates,  and  many  other  articles.  It  is  hard  and  brittle, 
and  more  readily  fusible  (1,530°  C.)  than  wrought  iron, 
which  is  made  from  it  by  remelting  and  exposure  to  further 


270  IRON  AND  ITS  COMPOUNDS 

IRON  (Continued)— 

oxidation  to  burn  off  the  carbon  and  other  impurities.     The 
output  of  pig  iron  in  1913  was  about  10,250,000  tons. 

Wrought  Iron  (melting-point,  1,600°  C.),  when  heated  to 
redness,  is  soft,  and  can  be  hammered  and  joined  (welded) 
into  any  desired  shape,  a  property  which  is  utilized  in 
smithcraft. 

The  purest  form  of  commercial  iron  is  the  fine  malleable 
quality  of  which  wire  is  made. 

Steel  melts  at  about  1,350°  to  1,375°  C.  and  is  pro- 
duced from  wrought  iron,  which  is  practically  devoid  of 
carbon,  by  the  incorporation  of  carbon  to  the  extent  of 
from  07  to  17  per  cent.,  and  from  cast  iron  by  removing 
the  excess  of  that  impurity.  It  is,  in  practice,  mostly 
produced  by  either  blowing  or  otherwise  exposing  molten 
pig  iron  to  a  blast  of  air  which  burns  out  the  carbon, 
together  with  other  impurities,  including  silicon,  manganese, 
and  sulphur. 

During  the  recent  war,  the  electro-thermal  steel  furnace, 
which  up  till  then  had  produced  only  a  small  proportion  of 
the  metal  in  this  country,  came  more  into  use,  and  by  the 
end  of  1918  about  140  furnaces  of  various  types  were  in 
use  here,  with  a  production  of  150,000  tons  per  annum,  the 
output  being  principally  used  in  respect  of  bullet-proof 
plates,  aeroplanes,  motor-cars,  armour-piercing  shells,  and 
steel  helmets. 

It  is  stated  that  on  the  Tyne,  electro-thermal  steel  is  now 
being  manufactured  at  a  price  which  can  compete  with  the 
acid  open-hearth  steel,  owing  to  the  cheap  power  of  coke- 
oven  gas.  The  output  of  steel  in  this  country  in  1918 
amounted  to  9,500,000  tons. 

So-called  mild  steel  contains  from  o-i  up  to  about  0-4  per 
cent,  of  carbon ;  the  harder  varieties  contain  up  to  about 
2  per  cent.,  while  the  largest  amount  of  carbon  that  iron 
can  be  made  to  take  up  is  just  over  4  per  cent.,  correspond- 
ing to  the  formula  Fe5C. 

In  the  so-called  basic  Bessemer  process  the  lining  of  the 
converter  or  oxidizer  is  made  of  bricks  of  magnesian  lime- 
stone cemented  together,  instead  of  the  siliceous  acid 
material  named  ganister,  which  was  used  in  the  old 
Bessemer  process,  with  the  result  that  the  phosphorus  is 
removed  in  addition  to  the  other  associated  impurities,  and 
concentrated  in  the  slag. 

It  is  the  phosphorus  content  of  the  cast  or  pig  iron  that 
determines  to  some  extent  the  particular  process  to  be 


IRON  AND  ITS  COMPOUNDS  271 

IRON  (Continued)— 

adopted  for  making  steel  therefrom.  In  the  absence  of 
phosphorus  to  any  considerable  extent,  the  old  Bessemer 
process  suffices,  in  which  the  "  ganister  "  lining  of  the  con- 
verters is  employed,  air  being  blown  through  the  molten 
mass,  thus  getting  rid  of  the  carbon,  but  leaving  some 
phosphorus  and  sulphur  in  the  molten  metal,  which 
is  made  more  or  less  brittle  in  consequence.  The  basic 
lining  removes  these  impurities  as  already  explained.  In 
the  Siemens-Martin  process  of  steel-making,  the  cast  iron 
is  mixed  with  specially  picked  iron  ore  in  furnaces  with 
open  hearths  heated  by  producer  gas. 

In  the  manufacture  of  steel  for  industrial  employment 
many  other  metals  are  deliberately  introduced,  manganese, 
for  instance,  being  used  for  hardening  purposes  up  to  about 
i  per  cent,  in  the  so-called  Bessemer  and  open-hearth 
steels,  although  for  some  purposes  larger  quantities  are 
used ;  while  nickel  is  used  to  produce  a  toughening  effect, 
and  chromium,  tungsten,  molybdenum,  tantalum,  and 
vanadium  are  severally  employed  to  give  particular  pro- 
perties or  qualities  to  steels  destined  for  special  applications. 

Steel  containing  13  per  cent,  chromium  and  a  low  per- 
centage of  carbon — stainless  steel — has  been  rendered 
possible  only  by  the  electric  furnace,  which  is  necessary  for 
the  preparation  of  the  ferro-chromes  as  also  for  the  steel 
melting. 

The  hardening  is  brought  about  by  the  rapid  cooling  of 
steel  which  has  been  heated  to  a  high  temperature,  whilst 
the  tempering  of  steel  is  effected  by  reheating  the  hardened 
metal  to  a  temperature  much  lower  than  that  used  for 
hardening  it,  and  cooling  slowly. 

Ferro- Alloys — Iron  alloyed  with  from  12  to  16  per  cent, 
of  silicon  is  very  resistant  to  the  action  of  acids,  and  the 
use  of  this  alloy  has  largely  replaced  that  of  glass  and 
stone  ware  in  chemical  industry.  It  is  somewhat  brittle, 
and  vessels  made  of  it  will  not  withstand  great  internal 
pressure,  but  up  to  50  Ib.  per  square  inch  they  are  con- 
sidered safe. 

Ferro-Carbon-Titanium  is  an  alloy  containing  carbon 
which  is  sometimes  used  to  make  steel  tougher. 

Ferro-Cerium  is  an  alloy  containing  various  metals  of 
the  cerium  group,  and  is  used  in  preparing  cigar  lighters. 

Ferro-Chrome  contains  from  50  to  60  per  cent,  of 
chromium  and  5  to  9  per  cent,  of  carbon. 


272  IRON  AND  ITS  COMPOUNDS 

IRON  (Continued}— 

Ferro-Manganese  is  an  alloy  of  manganese  carbide  with 
iron,  and  contains  from  20  to  85  per  cent,  of  manganese. 

Ferro  -Molybdenum,  Ferro-Nickel,  and  Ferro-Phosphorus 
all  have  their  special  applications  in  steel-making  of 
various  qualities,  the  latter  being  used  when  very  thin 
castings  have  to  be  made  by  increasing  the  fluidity  of  the 
metal. 

Ferro-Silicon — An  alloy  of  silicon  and  iron  containing 
30  per  cent,  or  more  silicon,  but  no  carbon,  is  used  not 
only  in  hydrogen-making,  but  also  in  conjunction  with 
Ferro-Manganese  as  a  deoxidizing  agent  for  converting 
white  cast  iron  into  grey  iron,  and  in  steel  manufacturing. 

Ferro-alloys  are  used  in  the  steel  industry  to  remove 
oxygen  and  nitrogen  from  the  molten  steel,  or  to  introduce 
into  the  steel  a  small  proportion  of  the  metal  in  order  to 
adapt  it  to  special  applications. 

To  remove  oxygen,  ferro-manganese,  ferro-silicon  con- 
taining 30  per  cent,  or  more  silicon,  ferro-aluminium,  and 
ferro-titanium  are  used  in  very  small  proportions,  the 
manganese  compound  being  most  generally  used  by  reason 
of  its  cheapness.  From  0*5  to  ro  per  cent,  of  metal  is  thus 
introduced. 

To  remove  nitrogen,  ferro-vanadium  containing  from  25 
to  40  per  cent,  vanadium  and  ferro-titanium  are  employed ; 
whilst  to  introduce  the  proportion  of  special  metal,  ferro- 
manganese,  ferro-vanadium,  ferro-chromium,  ferro-tungsten, 
ferro-molybdenum,  ferro-titanium,  ferro-uranium,  ferro- 
boron,  and  ferro- zirconium  are  all  used. 

A  steel  containing  12  to  14  per  cent,  manganese  is  very 
tough  and  hard  and  specially  adapted  for  mining  and 
grinding  machinery  and  making  burglar-proof  vaults ;  one 
containing  from  2  to  4  per  cent,  chromium  is  a  very  hard 
tool-making  material;  that  containing  15  to  25  per  cent, 
tungsten  is  a  high-speed  steel  which  will  cut  iron  while 
red-hot ;  that  containing  6  to  10  per  cent,  molybdenum  is 
similar  to  the  tungsten  variety  and  is  used  for  lining  large 
guns  to  increase  their  resistance  to  erosion. 

Steel  containing  from  0-5  to  ro  per  cent,  vanadium  is 
very  strong,  resists  shock  well,  and  is  used  for  making 
motor-car  axles,  cranks,  piston-rods,  etc.  The  titanium 
combination  containing  from  i  to  2  per  cent,  of  that  metal 
is  largely  used  for  making  steel  rails  and  sheet-steel. 

The  steel  containing  about  0-5  per  cent,  of  uranium  is 
said  to  replace  that  containing  several  per  cent,  of  tungsten, 


IRON  AND  ITS  COMPOUNDS  273 

IEON  (Continued)— 

and  is  used  for  making  tools  ;  while  the  zirconium  variety 
is  well  adapted  for  bullet-proof  sheets,  armour-plate,  and 
armour-piercing  projectiles. 

Slag  (known  as  Basic  Slag)  resulting  from  the  manufac- 
ture of  iron  and  steel,  containing  phosphorus,  finds  great 
employment,  when  reduced  to  powder,  as  a  fertilizing  agent. 
(See  Slag.) 

So-called  "slag-wool"  is  made  from  slag  by  blowing 
steam  against  it  when  in  melted  form,  being  thereby  con- 
verted into  fine  threads  like  cotton-wool,  and  in  this  form 
it  is  used  as  a  covering  for  steam-pipes  and  boilers,  and 
as  a  packing  material. 

Iron  Oxides. — The  three  known  oxides  of  iron  are  ferrous 
oxide  (FeO),  ferric  oxide  (Fe2O3),  and  the  so-called  mag- 
netic oxide  (Fe.jO4,  or  FeO,Fe2O3),  the  ferrous  and  ferric 
salts  being  derived  from  the  first  two  named  oxides  by 
t  combination  with  acids. 

Ferrous  Oxide  (FeO)  is  a  black  powder  which  oxidizes 
in  the  air.  In  combination  with  water  as  ferrous  hydroxide 
(Fe(HO)2),  it  is  precipitated  when  potassium  hydroxide 
solution  is  added  to  a  solution  of  a  ferrous  salt,  but  it 
rapidly  absorbs  oxygen  from  the  air  and  passes  into  the 
ferric  oxide  (Fe2(HO)6). 

Rust  consists  of  a  mixture  of  the  two  hydrated  oxides 
and  ferrous  carbonate,  and  continued  exposure  to  air  effects 
the  oxidation  of  the  ferrous  compounds  into  ferric  oxide 
(Fe203). 

Ferric  Oxide,  by  reason  of  its  hardness,  is  much  used  for 
grinding  and  polishing,  and  bloodstone  (a  hard  kind  of  red 
haematite)  when  well  polished,  is  considered  the  best  material 
for  producing  a  high  lustre  on  coat  buttons  and  on  the 
gilding  of  porcelain.  In  the  pulverulent  form,  the  ferric 
oxide  obtained  by  the  combustion  of  ferrous  oxalate  and 
other  methods  is  much  esteemed  for  its  grinding  and 
polishing  characters.  Jewellers'  rouge  for  polishing  gold 
and  silver  is  produced  by  lightly  calcining  ferrous  sulphate, 
while  the  article  named  " crocus"  used  for  polishing  brass 
and  steel,  is  produced  by  further  calcination. 

Ferric  oxide  is  also  used  for  colouring  glass  and  porcelain. 
Red  ferric  oxide  paint  is  an  important  article  of  commerce, 
and  considerable  quantities  are  made  in  the  provinces  of 
Jaen  and  Malaga  from  haematite  ore,  which  is  ground  and 
washed  with  water,  the  finest  powder  being  collected  and 

18 


274  IRON  AND  ITS  COMPOUNDS 

IRON  (Continued)  — 

dried.  After  making  it  into  paint,  it  is  used  extensively  for 
ships'  bottoms  and  iron  work,  and  as  a  colouring  matter 
for  paper,  rubber,  tiles,  etc.  The  high  grades  of  Spanish 
oxides  contain  from  80  to  95  per  cent,  of  Fe2O3. 

Ferric  Chloride  (FeCl3)  can  be  made  by  exposing  iron 
to  the  action  of  dry  chlorine,  and  in  combination  with 
water,  in  the  form  of  yellow  deliquescent  crystals 
(FeCl3,6H2O)  by  dissolving  iron  in  aqua  regia,  or  ferric 
oxide  in  hydrochloric  acid,  and  crystallization  of  the 
solution.  It  is  soluble  in  water,  is  used  in  medicine,  chlorina- 
tion  of  silver  and  copper  ores,  and  as  a  mordant  in  dyeing. 

Ferric  Sulphate  (Fe2(SO4)3)  can  be  prepared  by  the  action 
of  sulphuric  or  nitric  acid,  or  both,  on  ferrous  sulphate  in 
solution  — 


4H20+3Fe2(S04)3 

and  is  obtained  by  evaporation  of  the  solution  as  an  an- 
hydrous salt. 

A  combination  with  water  (Fe2(SO4)3,9H2O  )  is  also  known  . 

Ferric  sulphate  is  used  to  some  extent  in  medicine,  in 
pigment  -  making,  and  for  the  coagulation  of  blood  in 
abattoirs,  etc. 

A  double  sulphate  of  iron  and  potassium  known  as  iron 
alum  (K2SO4,Fe2(SO4)324H2O)  can  be  prepared  in  the  form 
of  violet  octahedra  by  dissolving  the  proper  quantity  of 
potassium  sulphate  in  a  strong  solution  of  ferric  sulphate 
at  o°  C.and  crystallization. 

Ferric  Ammonium  Sulphate  (Fe(NH4)(SO4)2i2H2O)  is 
a  violet  efflorescent  salt,  soluble  in  water,  used  in  textile 
dyeing,  etc. 

Ferric  Ammonium  Citrate  —  A  bronze  hygroscopic 
crystalline  salt  used  in  photography  and  medicine. 

Ferric  Acetate  (Fe2(C2H3O2)6)—  A  reddish  crystalline 
salt,  soluble  in  water,  used  in  textile  dyeing. 

Ferrous  Hydroxide  (Fe(HO)2)  is  produced  by  adding  an 
alkaline  hydrate  solution  to  a  ferrous  solution,  in  the  form 
of  a  whitish  precipitate  which  in  contact  with  air  rapidly 
absorbs  oxygen  and  passes  into  the  dark-coloured  ferric  oxide. 

Ferrous  Chloride  (FeCl2)  —  used  as  a  mordant  and  in 
metallurgy  —  can  be  obtained  in  pale  blue-green  crystals 
in  combination  with  water  (Fe,Cl2,4H2O)  by  dissolving 
iron  in  hydrochloric  acid,  and  evaporation  of  the  solution. 
The  anhydrous  chloride  is  produced  when  iron  wire  is 


IRON— IRONSTONE  275 

IRON  (Continued)— 

heated  in  gaseous  hydrochloric  acid,  the  chloride  volatilizing 
and  subliming  in  white  deliquescent  crystals. 

Ferrous  Sulphate  or  Green  Vitriol  (FeSO4,7H2O)  results 
from  dissolving  metallic  iron  in  dilute  sulphuric  acid  and  is 
obtained  upon  evaporation  of  the  resulting  solution,  in 
pale  green  crystals  of  an  efflorescent  character,  which  are 
soluble  in  water  (70  parts  in  100  at  15°  C.).  Upon  heat- 
ing to  100°  C.  these  crystals  lose  6  molecules  of  water  and 
the  residual  compound  is  therefore  FeSO4,H2O. 

Ferrous  sulphate  is  used  in  making  inks,  pigments,  and 
other  articles. 

Ferrous  Acetate  (Fe(C2H3O2)2)  is  extensively  used  under 
the  name  of  "  iron  liquor  "  as  a  mordant  in  dyeing. 

Iron  combines  with  sulphur  to  form  several  distinct 
sulphides  (FeS,  Fe2S3,  and  FeS2),  the  last  named  being 
found  in  nature  in  large  quantities  as  iron  pyrites  ;  there  is 
also  a  so-called  magnetic  pyrites  (Fe3S4)  found  in  hexagonal 
crystals  of  a  magnetic  character. 

Ferrous  Sulphide  (FeS)  is  a  nearly  black  compound, 
insoluble  in  water,  and  in  a  fused  form  is  used  for  gener- 
ating hydrogen  disulphide  by  the  action  of  acids  thereon. 
It  also  finds  employment  for  generating  sulphur  dioxide  by 
burning,  in  the  sulphite  process  of  preparing  wood  pulp. 

Ferrous  Oxalate  (FeC2O42H2O)  can  be  obtained  in  the 
form  of  pale  yellow  crystals,  insoluble  in  water,  and  is 
used  as  a  photographic  developer. 

Ferrous  Iodide  (FeI24H2O)  is  a  crystalline  body  soluble 
in  water,  and  is  used  in  the  manufacture  of  alkali  metal 
iodides. 

Ferrous  Fluoride  (FeF28H2O)  is  a  heavy  white  substance 
used  in  ceramics  and  in  the  manufacture  of  alkaline 
fluorides.  (See  also  Ferrocyanides  and  Prussian  Blue.) 

IRON  PYRITES— Iron  sulphide.     (See  Pyrites.) 

"  IRONAC "-  A  proprietary,  hard,  silicon  cast  iron  alloy, 
advocated  for  use  in  making  chemical  plant  to  withstand 
the  corrosive  action  of  acids. 

IRONE — A  methyl  ketone  (C13H20O)  constituting  the  odorifer- 
ous constituent  of  the  iris  root,  and  possibly  that  of  the 
violet :  it  can  be  prepared  from  citral. 

IRONSTONE— See  Iron. 


276  IRRIGA  TION—ISOMERISM 

IRRIGATION  is  a  process  often  employed  for  the  disposal  of 
sewage,  and  consists  in  allowing  it  or  the  effluent  from  it 
(after  preliminary  treatment  or  deposition  of  the  more  solid 
parts)  to  slowly  drain  off  or  filter  through  the  land,  over 
which  it  should  be  fairly  evenly  distributed.  A  light  loamy 
soil  is  the  most  suitable,  and  great  purification  is  effected, 
whilst  the  land  is,  at  the  same  time,  fertilized  for  the  growth 
of  cereals  and  vegetables.  The  nature  of  the  purification 
that  occurs  is  explained  under  the  heading  of  Nitrification. 
As  supplies  of  suitable  land  are  not  generally  available, 
specially  prepared  bacterial  filter-beds  of  ashes  or  charcoal 
and  other  materials  have  recently  come  into  more  general 
use.  (See  Nitrification  and  Sewage.) 

ISAROL — A  substitute  for  ichthyol  (made  from  bituminous 
schist  found  in  the  Tyrol)  used  as  an  irritant  in  skin  affec- 
tions. 

ISATIN  (C8H6NO2) — A  synthetic  reddish-yellow  crystalline 
substance,  fairly  soluble  in  hot  water,  ether,  and  alcohol, 
which  can  be  prepared  by  the  oxidation  of  indigo  with 
nitric  acid  and  is  convertible  into  aniline  by  the  action 
of  potash.  Its  melting-point  is  200°  C.,  and  it  is  used  in 
dyeing. 

ISINGLASS  (Ichthyocoll) — A  pure  commercial  form  of  gelatin 
made  from  the  internal  membranes  of  the  bladders  of  the 
sturgeon,  and  used  as  an  adhesive,  also  for  clarifying  wines, 
beers,  and  other  preparations.  An  inferior  sort  is  made  from 
fish  bones.  (See  Fish  Glue.) 

ISOLOGOUS — Having  similar  proportions  or  relations,  as,  for 
example,  groups  of  homologous  terms  in  which  radicals,  by 
combining  with  a  series  of  similar  elements,  produce 
other  series  of  similar  compounds. 

ISOMERISM — Substances  composed  of  the  same  number  of 
the  same  atoms  but  differing  in  molecular  construction  and 
properties  are  described  as  isomeric.  Thus,  ordinary  alcohol 
and  methyl  ether  have  the  same  percentage  composition 
and  molecular  formula  (C2H6O),  but  are  perfectly  distinct 
substances,  the  constitutional  formulae  being  respectively 
C2HgHO  and  (CH3)2O.  There  are  many  such  cases,  par- 
ticularly amongst  organic  compounds,  and  notably  in 
connection  with  the  bodies  known  as  terpenes — that  is,  the 
hydrocarbons  forming  the  chief  constituents  of  the  various 
essential  oils — all  of  which  have  the  common  formula 
C10H16,  and  yet  differ  largely  in  their  chemical  and  physical 


ISOMERISM— ISOTOPES  277 

ISOMERISM  (Continued)— 

properties.  They  are  therefore  described  as  physical 
isomers.  Varying  amounts  of  heat  are  consumed  in  the 
formation  of  any  two  isomeric  bodies,  and  so  when  decom- 
posed, there  is  a  corresponding  difference  in  the  evolution  of 
heat,  showing  that  varying  amounts  of  energy  are  required 
to  build  up  the  different  molecular  structures  of  isomeric 
bodies. 

Stereo-isomerism — Isomerism  arising  from  the  rearrange- 
ment in  space  of  the  atoms  or  radicals  in  a  molecule  round 
a  central  polyvalent  atom. 

Thus  two  compounds  may  contain  the  same  atoms  and 
radicals,  and  have  identical  chemical  and  physical  proper- 
ties, and  yet  differ  in  their  action  upon  polarized  light. 

In  the  case  of  active  carbon  compounds,  these  atoms  and 
molecules  are  four  in  number,  and  if  they  are  imagined  to 
occupy  the  corners  of  a  tetrahedron  containing  the  quadri- 
valent carbon  at  its  centre,  then  it  will  be  found  that  such 
an  arrangement  necessitates  two  "stereo"  or  space  isomers, 
which  correspond  to  the  positive  and  negative  varieties  of 
the  compound.  Valeric  acid  (C5H10O2),  for  example,  apart 
from  its  other  modifications,  possesses  two  stereo-isomers, 
and  the  groupings  in  this  case  are  the  four  different  radicals 
H,  CH3,  C2H5,  and  CO2H.  (See  Polymerism  and  Allo- 
tropy.) 

ISOMORPHISM— See  Crystallization. 

ISOPRENE  (C5H8)— A  volatile  liquid  hemi-terpene,  yielded  by 
the  destructive  distillation  of  pure  rubber,  also  obtainable 
from  turpentine  by  the  action  of  heat,  and  which  by  contact 
with  certain  reagents,  such  as  hydrochloric  acid,  becomes 
converted  partly  into  rubber.  It  is  colourless,  boils  at 
37°  C.,  and  is  of  interest  in  connection  with  the  attempted 
synthesis  of  rubber  on  a  commercial  scale.  (See  Rubber.) 

ISOTOPES — A  term  introduced  to  explain  the  apparent  exis- 
tence of  very  nearly  allied  but  non-separable  forms  of 
chemical  elements,  the  general  chemical  properties  being 
identical,  but  exhibiting  variation  in  their  atomic  weights, 
or  mass,  or  molecular  arrangement.  Thus  it  is  supposed 
that  magnesium,  silicon,  and  chlorine,  in  addition  to  neon, 
are  mixtures  of  isotopes ;  further,  that  nickel,  copper,  zinc, 
mercury,  and  other  of  the  elements,  are  really  mixtures  of 
isotopes.  Ionium  and  thorium  are  said  to  be  isotopes. 
Many  of  the  conclusions  of  the  investigators  of  these 


278  ISOTOPES— JA  SPER 

ISOTOPES  (Continued)— 

matters  are  based  upon  radio-active  evidence,  and  others 
upon  the  separation  of  gases  by  diffusion,  but  much  remains 
to  be  done  before  the  subject  and  the  electron  constitution 
of  matter  can  be  regarded  as  satisfactorily  established. 
(See  Atoms,  Radio-activity,  Protyle,  and  Spectroscope.) 

IVORY — Essentially  dentine ;  the  main  constituent  of  all  teeth, 
containing  about  57  to  60  per  cent,  calcium  salts  (chiefly 
phosphate)  and  40  to  43  per  cent,  organic  matrix. 

IVORY  BLACK — A  fine  velvety  carbonaceous  black,  largely 
composed  of  mineral  matter  (65  to  75  per  cent.),  including 
calcium  phosphate,  prepared  by  carbonizing  ivory-turnings 
and  waste,  and  used  by  copper-plate  printers  in  making 
their  ink,  also  as  a  decolourizing  and  filtering  agent. 

"  IZAL  " — A  proprietary  disinfectant,  being  a  ready  prepared 
emulsion  of  phenoloids. 

JABORANDI— See  Pilocarpine. 

JADE — Several  distinct  minerals  are  known  by  this  name,  the 
true  jade  being  naphrite,  an  anhydrous  double  silicate  of 
calcium  and  magnesium.  Jadeite,  which  resembles  it,  is  a 
silicate  of  aluminium  and  sodium.  Jade  is  greenish-white 
to  deep  green  in  colour,  is  a  favourite  material  for 
making  ornaments  and  amulets,  and  is  nearly  as  hard  as 
quartz.  It  is  extensively  found  in  China,  New  Zealand, 
Eastern  Turkestan,  Siberia,  and  the  Philippine  Islands. 

JALAP — The  root  of  the  plant  Ipomoea  purga  (Off. — Exogonium 
purga  U.S.),  which  grows  in  Mexico,  and  is  cultivated  in 
India.  It  furnishes  about  10  per  cent,  glucosidal  resins, 
containing  about  90  per  cent,  convolvulin  (C31H50O16)  and 
about  10  per  cent,  jalapin  (C34H56O16).  The  resin  con- 
stitutes a  powerful  purgative. 

JAPAN — A  lacquer  for  metallic  and  wooden  articles,  made  by 
heating  a  mixture  of  linseed  oil,  litharge,  and  Prussian 
blue,  thinned  with  turpentine  or  naphtha. 

JAPAN  WAX— See  Waxes. 

JAPANNING — A  sort  of  varnishing  or  lacquering  in  which 
the  Japanese  excel,  consisting  in  heating  the  varnished 
articles,  after  application  of  each  coat,  in  an  oven  to  a 
high  temperature.  Ivory  black  and  anime  varnishes  are 
used  amongst  other  materials,  colours  being  introduced 
as  and  when  required. 

JASPER — A  kind  of  quartz.     (See  Silica.) 


JATROPHA—KAUREI  GUM  279 

JATROPHA — A  genus  of  euphorbiaceous  plants,  the  root  of 
one  of  which  (Jatropha  manihot)  yields  arrowroot. 

JAVELLE— See  Eau  de  Javelle. 

JET — Supposed  to  be  wood  in  an  advanced  state  of  bitumeni- 
zation  (lignite),  abundant  in  the  upper  lias  shale  near 
Whitby  in  Yorkshire.  It  is  also  found  in  Colorado,  the 
island  of  Skye,  and  various  parts  of  the  European  continent, 
and  is  used  as  fuel  and  for  making  ornamental  articles.  It 
is  of  varying  hardness  and  of  sp.  gr.  about  i'3. 

"JEYES'  FLUID" — A  disinfectant  made  from  coal  tar  prin- 
ciples, miscible  with  water. 

JUNIPER — Coniferous  plants,  of  which  about  twenty  species 
are  known  (including  Junipents  communis  and  /.  Phoenicia), 
the  berries  of  which  yield  upon  distillation  with  water,  a 
volatile  essential  oil,  of  sp.  gr.  0*865  to  0*882  ;  iodine  value, 
about  285;  saponification  value,  14  to  15;  and  refractive 
index,  1*472  to  i^SS.  It  is  somewhat  soluble  in  alcohol 
and  ether,  and  is  used  for  flavouring  gin  and  hollands. 

JUTE — The  bast  fibre  of  the  Corchorus  capsularis,  the  culture  of 
which  is  chiefly  carried  on  in  Bengal.  It  is  extensively 
manufactured  in  Dundee,  and  is  woven  in  India  into 
gunny  bags  and  cloth,  which  are  largely  used  in  the  Southern 
States  of  America  for  cotton  packings.  It  is  also  used  in  the 
manufacture  of  carpets  and  various  tissues,  twine,  and  paper. 

KAINITE— See  Potassium. 

KAOLIN  (Terra  Alba,  China  Clay,  White  Bole)  is  not  only 
used  in  ceramics  and  in  compounding  some  pigments,  but 
also  for  mixing  with  graphite  in  pencil-making.  Its  general 
formula  may  be  regarded  as  Al2O3,2SiO2,2H2O.  (See  Clays.) 
"Emol  Keleet"  is  a  refined  preparation  of  kaolin  used 
for  pharmaceutical  preparations.* 

KAPOK — The  Malay  name  given  to  the  cotton-like  down 
produced  in  the  seed-pods  of  the  tree  of  that  name  and 
extensively  used  in  making  life-saving  jackets,  etc.  The 
dried  seeds  yield  about  24-5  per  cent,  of  oil. 

"  KARBOS  " — A  char  made  from  charred  sawdust  purified  by 
acid  treatment,  and  admixed  with  animal  carbon  ;  used  for 
decolourizing. 

KAURIE  GUM— A  product  of  the  kaurie  pine  of  New 
Zealand.  There  is  a  large  deposit  of  kaurie  gum  peat  in 
the  soil  of  the  buried  kauri  forest  in  New  Zealand,  and 
a  considerable  industry  is  carried  on  in  the  extraction  of 
the  gum  and  associated  oils,  A  ton  of  the  peat  yields 


280  KAURIE  GUM— KELP 

KAUEIE  GUM  (Continued)— 

about  10  per  cent,  of  gum  and  gives  by  distillation  about 
64 J  gallons  of  oil,  from  which  motor  spirit,  a  solvent  oil, 
a  turpentine  substitute,  and   paint   and   varnish   oils   are 
extracted.     The  sp.  gr.  of  kaurie  is  1*05  and  the  melting- 
point  about  from  182°  to  232°  C.;  it  is  used  in  varnish- 
making  and  the  preparation  of  dental  compounds.     (See 
Dammar  and  Resins.) 

KELP — The    ashes    of   burnt    seaweeds,   containing    sodium 
carbonate,  sulphate,  and  sulphide,  together  with  the  chlorides 
.  of  potassium  and  sodium,  and  insoluble  substances  com- 
prising calcium  carbonate,  silica,  and  alumina.     Kelp  was 
at   one   time   used  for  the  extraction  of  both  alkali  and 
iodine,  the  latter  being  recovered  from  the  mother-liquor 
remaining  after  the  crystallization  of  the  salts  from  the 
extracted  ashes.     Two  published   analyses  give  the  per- 
centic  parts  as  follows : 
Potassium  sulphate  ...  ...       8  -0-19-0 

Soda  as  carbonate  and  sulphide       8-5-  5-5 
Potassium  and  sodium  chlorides   36-5-37-5 


53-0-62-0  soluble  part. 
47-0-38-0  insoluble  part. 

In  one  process,  the  dried  kelp  is  fed  into  a  retort  kept  at 
a  temperature  of  about  980°  C.  to  obtain  oil,  creosote, 
ammonia,  etc.,  by  distillation,  and  the  charred  residual  mass 
is  cooled,  ground  and  lixiviated,  first  of  all  with  a  concen- 
trated brine,  fresh  water  being  used  for  the  final  extraction. 

The  pressed  coke  is  saturated  successively  with  hot 
hydrochloric  acid  and  water,  and  is  afterwards  used  as  a 
decolourizing  agent. 

After  removal  of  trie  sulphates  from  the  brine  liquor,  it 
is  heated  in  a  vacuum  pan  to  a  certain  point  of  concentra- 
tion and  then  transferred  to  a  vacuum  crystallizer,  in  which 
the  potassium  chloride  deposits.  Upon  further  concentra- 
tion the  sodium  chloride  separates,  whilst  from  the  mother- 
liquor  iodine  is  obtained. 

In  another  process,  the  kelp  is  fed  into  one  end  of  a 
rotary  kiln,  in  which  it  encounters  a  flame  of  burning  oil 
from  the  other  end,  thus  producing  a  charcoal-like  mass 
which  is  subsequently  quenched,  ground  and  leached  (lixi- 
viated), or  it  may  be  burned  to  a  grey  loose  ash  with  a 
potassium  content  equal  to  about  35  per  cent.  K2O. 

About  8  Ibs.  iodine  can  be  extracted  from  a  ton  of  Scotch 
kelp. 


KERATIN— KIESELGUHR  281 

KERATIN — A  gelatinous  substance  obtained  from  hoofs,  nails, 
and  hair  of  animals. 

KERMES — The  dried  bodies  of  a  female  insect  (Coccus  ilicis 
L.),  collected  in  Africa  and  some  eastern  parts  of  Europe, 

*  and  used  for  dyeing  scarlet  "  fez  "  skull-caps,  but  the  colour 
has  less  bloom  than  that  given  by  cochineal,  and  is  chemic- 
ally related  to  carminic  acid. 

KERMES  (Mineral) — A  mineral  form  of  antimony  sulphide. 
"KEROL" — A  proprietary  phenoloid  disinfectant  liquid  which 
emulsifies  with  water. 

KEROSINE — A  mineral  illuminant  oil  distilled  from  the  natural 
petroleum  deposits  in  America,  free  of  gasoline,  naphtha, 
and  heavy  oils.  Sp.  gr.  about  i  -440  and  boiling-point  about 
230°  to  240°  C. 

KETONES — A  class  of  organic  bodies,  produced  by  the 
oxidation  of  the  secondary  alcohols.  They  are  nearly 
related  to  the  aldehydes,  from  which  they  may  be  considered 
as  derived  by  the  displacement  of  H  in  the  COH  group  by 
the  alcohol  radicals.  Thus  common  ethyl  aldehyde  (C2H4O 
or  CH3COH)  becomes  CH3CO(CH3)— the  formula  of 
dimethyl  ketone,  or,  as  it  is  commonly  called,  acetone 
(C3H6O) — which  is  the  lowest  member  of  the  series. 

Again,  iso-propyl  alcohol  by  oxidation,  yields  acetone  by 
the  withdrawal  of  two  hydrogen  atoms — 

C3H8O  or  CH3CH(OH)CH3  +  O  = 
CH3(CO)CH3  (Acetone)  +  H2O. 

"  KHARSIVAN  "—The  name  of  a  British  make  of  salvarsan. 

KIESELGUHR  (Infusorial Earth,  Tripolite)— A  soft,  white,  earthy 
deposit  of  hydrated  silica,  being  the  siliceous  skeletons  of 
minute  aquatic  plants  known  as  diatoms,  found  in  Germany, 
the  United  States,  and  many  other  parts  of  the  world.  It 
is  generally  associated  with  earthy  impurities,  and  contains 
from  65  to  87  per  cent.  SiO2,  2-3  to  11*7  per  cent.  A12O3, 
up  to  3  per  cent.  Fe2O3,  small  proportions  of  the  oxides 
of  calcium,  magnesium,  potassium,  and  sodium,  and  from 
5  to  14  per  cent,  water. 

It  is  of  great  absorbent  capacity,  capable  of  taking  up 
about  four  times  its  own  weight  of  water  and  having  a 
sp.  gr.  of  about  0-33. 

It  is  largely  used  as  an  absorbent  for  carrying  liquid 
petroleum,  in  the  manufacture  of  dynamite,  as  a  filtering 
material,  in  ceramics,  as  an  abrasive,  cleanser,  and  polishing 
agent,  and  in  compounding  mixtures  for  boiler  coverings, 

•  etc.     (See  Silicon.) 


282  KIESERITE— KRYPTON 

KIESERITE— Mineral  magnesium  sulphate  (MgSO4,H2O) 
found  in  the  Stassfurt  salt  deposits. 

KIMMERIDGE  CLAY  or  SHALE— A  deposit  found  under  the 
sands  beneath  the  Portland  stone  of  Dorsetshire  and  else- 
where, abounding  in  animal  and  vegetable  matters.  It- 
is  used  to  some  extent  as  fuel  and  yields  on  distillation 
petroleum-like  products. 

KINGZETT'S  SULPHUR  CANDLES— See  Sulphur. 

KINO — The  concreted  (inspissated)  juice  of  at  least  four  varieties 
of  trees,  used  as  a  drug,  being  of  an  astringent  character. 

African  kino,  or  gummi  gambia,  comes  from  the  Pterocarpus 
eyinaceus ;  the  Asiatic  kind  from  Pterocarpus  marsupium  ; 
the  New  Holland  variety  from  the  Eucalyptus  resinifera ; 
and  the  American  kino  from  Coccoloba  urifeva. 

The  African  kino  is  particularly  rich  in  tannin,  and  is 
used  for  tanning  purposes  and  in  the  textile  industry. 

KIPP'S  APPARATUS— See  Gas  Generators. 

KIRSCHWASSER — An  alcoholic  liqueur  obtained  by  ferment- 
ing and  distilling  pulped  cherries. 

KISH — Crystalline  graphite  deposited  in  iron  furnaces  from 
molten  iron  upon  cooling. 

KNOPPERN  (Knopper  Galls) — A  tannin  material  in  the  form 
of  excrescences  produced  by  insects  (Cynips  calicis)  upon  the 
immature  acorns  or  flower  cups  of  certain  species  of  oak — 
principally  Quercus  cerris  of  the  Slavonic  plains — and  known 
as  "  sisarca  "  and  "  gubacs." 

KOKA-SEKI — A  variety  of  pumice  found  in  the  Niijima 
Islands,  used  as  a  building  material  and  for  the  construction 
of  reinforced  concrete  barges,  etc. 

KOLA  (COLA)  NUTS  (Soudan  Coffee)— From  the  seeds  of 
Cola  acuminata,  containing  caffeine. 

"  KOLLAO  "—See  Lubricants. 

KOUMISS  —  Fermented  mare's  milk  used  in  Tartary  as  a 
vinous  food ;  something  similar  is  said  to  be  made  in  the 
Orkneys.  An  intoxicating  spirit  called  "  rack  "  is  distilled 
from  koumiss. 

KRAMERIA — See  Rhatany  Root. 

KRYPTON  (Kr)  — Atomic  weight,  82*92.  A  very  rare  elemental 
matter  recently  isolated  from  liquefied  air,  and  present  in 
the  air  to  the  estimated  extent  of  i  part  in  1,000,000.  It  is 
a  colourless  and  inert  gas  and  no  chemical  compounds  of  it 
are  known. 


KUPFERNICKEL-LACTIC  ACID  283 

KUPFERNICKEL— See  Nickel  and  Arsenic. 

LABORATORY — A  simple  chemical  laboratory  (workshop)  con- 
sists essentially  of  a  working  bench  or  table  about  three  feet 
from  the  ground,  fitted  with  drawers  and  a  shelf  running 
along  the  back,  upon  which  can  be  placed  the  chemical 
solutions  (reagents)  which  are  more  or  less  in  daily  use. 
The  bench  should  be  provided  with  either  a  lead-lined 
wooden  or  a  porcelain  sink ;  a  water-supply  pipe  with 
one  or  more  taps  ;  also  a  gas-supply  pipe  with  two  or  three 
T-piece  connections  and  taps,  to  which  the  various  lamps 
and  burners  ordinarily  used  can  be  attached.  In  cupboards 
or  on  a  shelf  below,  may  be  placed  the  larger  pieces  of 
apparatus  and  supplies  of  chemicals  that  are  only  occasion- 
ally wanted,  whilst  the  drawers  in  the  bench  are  useful  for 
the  storage  of  small  appliances  and  requisites. 

LABRADORITE  (Labrodite) — A  mineral  of  the  lime-soda 
felspar  order  which  takes  a  beautiful  polish  and  exhibits 
changing  colours  (iridescence). 

LAC— See  Shellac. 

LACMOID  (Resorcinol  Blue) — An  indicator  used  in  volumetric 
analysis  ;  prepared  from  resorcinol  by  treatment  with  sodium 
nitrite. 

LACQUER — Varnish  consisting  of  shellac  dissolved  in  alcohol 
and  coloured  as  desired  with  saffron,  annato,  or  dragon's 
blood,  etc. 

LACTIC  ACID  (C3H6O3)  results  from,  and  is  largely  manu- 
factured by,  the  bacterial  fermentation  of  milk,  cane,  or  grape 
sugars,  using  the  lactic  bacilli  which  cause  the  acidity  of  soured 
milk.  As  thus  made  from  starch,  milk,  or  sugar,  the  acid 
is  neutralized  as  the  fermentation  proceeds  (at  a  temperature 
of  about  34°  C.)  by  addition  of  calcium  carbonate,  and  the 
solution  of  calcium  lactate  is  subsequently  concentrated 
and  decomposed  with  sulphuric  acid.  The  pure  liquid  acid 
has  a  sp.  gr.  of  about  i'2485,  is  soluble  in  water  and  alcohol, 
and  is  used  in  the  leather  and  textile  industries,  and  in 
mordanting,  etc. 

It  is  best  known  in  a  state  of  solution,  but  can  be 
obtained  in  a  crystalline  form  which  melts  at  18°  C.  It  is 
also  produced  by  the  action  of  caustic  potash  solution  upon 
grape  or  cane  sugar  with  heat.  For  commercial  purposes, 
lactic  acid  is  prepared  of  50  per  cent,  and  60  per  cent, 
volume,  and  of  50  per  cent,  volume  strength  for  edible  ap- 
plications. 

Upon   heating,   lactic   acid   is   partially  converted   into 


284  LACTIC  ACID—LANTHANITE 

LACTIC  ACID  (Continued)— 

lactide  (C6H8O4) — its  anhydride — and  when  heated  with 
dilute  sulphuric  acid  it  splits  up  into  acetaldehyde  and 
formic  acid.  All  the  lactates  are  soluble  in  water. 

Lactic  acid  is  said  to  be  rapidly  replacing  the  more 
expensive  citric  and  tartaric  acids  in  the  compounding  of 
soft  drinks  and  in  other  industrial  applications  in  the  United 
States  of  America,  and  a  small  addition  is  stated  to  improve 
the  quality  of  beer  of  low  alcohol  content  by  combining 
with  the  amides  and  amino-acids. 

LACTOSE  or  MILK  SUGAE  (C12H22On,H2O)— The  sugar 
contained  in  milk  (sugar  of  milk).  It  can  be  obtained  in  a 
crystalline  state,  and  is  prepared  on  a  considerable  scale 
in  Switzerland  and  elsewhere  from  the  whey  obtained  in 
cheese-making,  by  concentration  and  crystallization.  It  is 
sweet,  soluble  in  water,  and  used  in  the  preparation  of 
infants'  foods. 

L^VULOSE— See  Fructose. 

LAKES — The  pigments  obtained  by  precipitation  from  dye- 
stuffs  and  colouring  matters.  Aluminium  hydroxide 
(A1(HO)3)  enters  into  combination  with  many  soluble 
organic  colouring  matters,  thus  precipitating  them  as  so- 
called  "  lakes  "  in  calico  printing  and  dyeing.  (See  Alu- 
minium.) The  aluminium  hydroxide  acts  as  the  mordant, 
and  the  same  dye  can  give  rise  to  different  coloured  lakes 
according  to  the  nature  of  the  mordant  that  is  used.  The 
lakes  produced  from  certain  dyestuffs  are  useless  as  pig- 
ments owing  to  their  hard  and  horny  nature,  but  if  produced 
on  a  suitable  base  or  "  extender,"  such  as  barytes,  china 
clay,  blanc  fixe,  etc.,  this  difficulty  is  overcome.  Lakes  are 
also  used  in  the  preparation  of  some  lithographic  and 
printing  inks.  (See  Dyes  and  Dyeing.) 

LAMP-BLACK — A  finely  divided  carbonaceous  deposit  result- 
ing from  the  imperfect  combustion  of  natural  gas  and  lamp 
and  other  oils  and  fatty  substances.  The  blackening  of  the 
glass  chimney  of  a  paraffin  lamp  is  due  to  the  deposition  of 
lamp-black. 

It  is  manufactured  for  use  in  making  blacking,  black 
paint,  and  printer's  ink.  (See  Carbon.) 

LANARKITE— A  natural  basic  lead  sulphate  (PbSO4,PbO). 
LANOLINE— See  Adeps  Lanse. 

LANTHANITE — A  mineral  containing  lanthanum  carbonate 
associated  with  cerium  carbonate. 


LANTHANUM— LAUGHING  GAS  285 

LANTHANUM  (La) — Atomic  weight,  139;  sp.  gr.,  about  6-155; 
melting-point,  about  810°  C.  A  rare  element  of  the  cerium 
group,  found  in  cerite,  allanite,  and  lanthanite,  also  in  orthite 
in  Greenland,  and  in  association  with  other  elements  in 
gadolinite  (ytterbite).  It  is  a  metal  of  lead-grey  colour,  and 
decomposes  water  slowly  with  the  evolution  of  hydrogen. 
It  can  be  prepared  by  the  electrolysis  of  lanthanum  chloride. 
The  salts  of  lanthanum  in  solution  are  colourless,  and 
when  precipitated  with  a  solution  of  potash  or  soda  a  bulky, 
gelatinous  hydroxide  (La(OH)3)  is  formed. 

Lanthanum  forms  two  oxides  (the  better  known  of  which 
is  La2O3,  and  both  of  which  are  insoluble  in  water),  a 
chloride  known  in  the  anhydrous  state  (LaCl3)  (which  is 
soluble  in  alcohol,  and  in  a  crystalline  form  in  combination 
with  water),  also  a  number  of  other  compounds,  including 
the  nitrate  (La(NO3)36H2O),  the  sulphate  (La(SO4)39H2O) 
(both  of  which  are  crystalline  salts  soluble  in  water),  and 
the  carbonate  La2(CO3)3.3H2O,  which  is  used  in  making 
incandescent  gas  mantles. 

LAPIS  LAZULI — A  translucent  fine,  blue,  native  compound 
silicate  of  aluminium,  calcium,  and  sodium,  found  in 
crystalline  limestone  on  the  Indus,  and  in  granite  in 
Persia,  China,  and  Siberia.  It  is  highly  valued  as  a 
beautiful  mineral  for  vase-making,  and  at  one  time,  ultra- 
marine was  prepared  from  it. 

LARD — The  fat  of  the  hog,  containing  a  large  proportion  of 
olein  with  other  glycerides.  (See  Fats.) 

LATENT  HEAT  is  the  heat  absorbed  in  a  state  of  physical 
change,  such  as  that  of  solid  ice  to  liquid  water.  This 
particular  change  renders  latent  that  amount  of  heat  which 
would  serve  to  raise  the  temperature  of  the  same  weight  of 
water  through  79°  C.  (See  Heat.) 

LATEX — A  milky  juice  produced  in  plants  which  coagulates 
into  a  gelatinous  mass  in  cavities.  This  gelatinous  sub- 
stance is  called  cambium,  and  is  supposed  in  certain  cases 
to  precede  the  formation  of  cells.  Gutta-percha  is  the 
coagulated  product  of  latex  from  the  Isonarda  percha  tree. 

LAUDANUM — Tincture  of  opium,  prepared  by  dissolving 
granulated  opium  in  dilute  alcohol. 

LAUGHING  GAS  or  NITROUS  OXIDE— See  Nitrogen  Com- 
pounds (p.  338). 


286  LAUREL  OIL— LEAD 

LAUREL  OIL — A  bright,  yellow,  volatile  oil  of  aromatic  odour ; 
soluble  in  alcohol,  ether,  and  chloroform ;  distilled  from 
the  leaves  of  Laurus  nobilis,  and  used  in  medicine.  Its 
sp.  gr.  is  0*924. 

LAUBIC  ACID  (C12H24O2)— A  member  of  the  fatty  acid  series 
and  a  notable  constituent  of  oil  of  laurels  or  fat  of  the  bay- 
tree  (Laurus  nobilis).  It  can  also  be  obtained  from  pichurim 
beans  and  cocoa-nut  oil.  It  melts  at  43°  C.,  and  is  soluble 
in  hot  alcohol. 

LAURITE — A  very  rare  mineral  combination  of  ruthenium  as 
sulphide  (RuS2). 

LAVA — The  fused  material  thrown  out  by  volcanoes  when  in 
action,  largely  consisting  of  silicate  of  aluminium. 

LAVENDER  (SPIKE)  OIL— The  yellowish  essential  oil  of 
Lavandula  spica  L.,  consisting  in  part  of  a  terpene ;  sp.  gr., 
0-905  to  0-920;  optical  rotation,  o°  to  +3°;  soluble  in  alcohol, 
ether,  etc.,  and  used  in  perfumery  and  liniment-making. 

LAVENDER-FLOWER  OIL  is  distilled  from  the  flowers  of 
Lavandula  officinalis,  and  is  more  fragrant  than  the  spike 
oil.  It  is  nearly  colourless,  has  a  sp.  gr.  of  0-885  to  0-897, 
optical  rotation  -  5°  to  -  8°,  is  soluble  in  alcohol,  ether, 
etc.,  and  is  used  in  perfumery.  It  contains  linalool,  linalyl 
acetate,  geraniol,  and  cineol. 

LAZULITE  (Azurite) — A  mineral  crystalline  form  of  hydrated 
phosphate  of  aluminium,  magnesium,  and  iron. 

LEAD  (Plumbum,  Pb)  and  its  Compounds — Atomic  weight, 
207;  sp.  gr.,  11*3;  melting-point,  327-4°  C.  Lead  occurs 
naturally,  for  the  most  part,  in  the  form  of  galena  or  lead 
sulphide  (PbS),  the  U.S.A.,  Mexico,  and  Spain  providing 
the  principal  supplies.  It  also  occurs  as  carbonate 
(PbCO3)  in  cemsite  and  in  other  combinations  it  is  present 
in  anglesite  (PbSO4),  in  lanarkite  (PbSO4,PbO),  etc.,  whilst  a 
new,  rich  mine  has  been  recently  discovered  in  Burmah. 
The  production  of  lead  ores  on  certain  horizons  of  the 
lower  carboniferous  formations  in  England  and  the  Lower 
Palaeozoic  formations  in  Great  Britain  decreased  steadily 
from  80,850  tons  in  1877  to  14,784  tons  in  1918.  In  1913 
the  world's  production  of  lead  was  1,700,000  tons. 

Lead  is  produced  by  several  processes,  one  of  which 
consists  in  roasting  lead  sulphide  in  a  reverberatory  furnace 
at  a  certain  temperature,  whereby  some  of  it  is  resolved 
into  lead  sulphate  (PbSO4)  and  some  into  lead  oxide  (PbO), 
a  part  of  the  sulphur  being  burnt  off  as  sulphur  dioxide 


LEAD  287 

LEAD  (Continued)  — 

(SO2).  Upon  increasing  the  temperature,  a  further  change 
takes  place  in  the  mixture  which  still  contains  some  lead 
sulphide,  and  metallic  lead  results  from  the  two  following 
interactions  : 

.!  +  PbS  =  2Pb  +  2SO2 


The  metallic  lead  thus  produced  is  subsequently  refined  by 
another  process. 

In  other  metallurgical  processes,  a  saturated  solution  of 
salt,  which  is  a  good  solvent  for  lead  chloride  and  lead 
sulphate,  is  used,  and  from  the  solutions  so  obtained  (when 
not  contaminated  with  other  elements)  the  oxide  is  pre- 
cipitated by  the  action  of  lime,  or  (when  contaminated  with 
other  elements)  by  electrolysis,  the  metallic  lead  being 
obtained  from  the  oxide  by  reduction. 

From  recent  investigations  of  metallic  lead  as  obtained 
from  radio-active  minerals  —  that  is,  minerals  containing 
uranium  and  radium  —  it  would  appear  that  there  are,  at 
least,  two  kinds  (isotopes)  of  lead  —  viz.,  the  ordinary  type  as 
found  in  non-radio-active  minerals,  and  another  which  is 
assumed  to  be  produced  by  the  decomposition  of  uranium, 
this  radio-active  form  showing  a  slightly  higher  (o'O5°  C.) 
melting-point  than  that  of  ordinary  lead. 

The  density  of  the  uranio-lead  was  originally  reported  as 
below  that  of  the  ordinary  metal,  as  also  its  atomic  weight 
(206)  .  A  specimen  of  lead  prepared  from  a  Norwegian  thorite 
(from  Langesundfiord)  quite  recently  examined,  containing 
30'  i  per  cent,  thorium,  0*45  per  cent,  uranium,  and  0-35  per 
cent,  lead,  appeared,  however,  to  have  an  atomic  weight  of 
207-77,  the  highest  value  yet  assigned  to  this  element,  so  that 
the  matter  cannot  be  regarded  as  definitely  settled,  and  more 
delicate  processes  of  analysis  are  required  to  clear  up  the 
existing  doubt  as  to  the  existence  of  distinct  metallic  leads. 

Lead  is  a  heavy,  bluish-  white  metal,  very  soft  in  character, 
but  not  very  ductile  or  tenacious,  and  it  readily  tarnishes 
upon  exposure  to  the  air.  Owing  to  its  soft  character  it 
is  easily  worked,  and  it  is  consequently  employed  very 
largely  for  lining  wooden  cisterns,  making  water-pipes, 
gutters  and  roofing,  as  also  shots,  and  in  the  preparation  of 
white  lead  and  various  alloys.  It  can  be  hardened  by 
alloying  it  with  a  small  proportion  of  metallic  sodium. 

Type-metal  consists,  in  part,  of  lead  (alloyed  with  antimony 
and  tin),  and  lead  is  also  used  in  the  manufacture  of  fusible 


288  LEAD  AND  ITS  COMPOUNDS 

LEAD  (Continued)— 

metal,  pewter,  and  other  alloys.  Solder,  as  used  by  plumbers 
and  tin-plate  workers,  is  a  mixture  of  lead  and  tin  in 
proportions  varying  with  the  particular  applications  to  be 
made  of  it,  whilst  so-called  pot-metal  is  an  alloy  of  lead  and 
copper. 

Many  of  the  compounds  of  lead  are  largely  used  in  the 
arts  and  manufactures. 

White-Lead,  which  is  used  so  much  in  compounding 
paints  and  putty,  is  a  mixture  of  lead  carbonate  and 
hydrated  lead  oxide. 

Of  the  various  processes  for  making  white-lead,  the  oldest 
and  best  is  the  so-called  Dutch  process,  which  depends 
upon  the  use  of  acetic  acid  in  association  with  moist  air 
and  carbon  dioxide.  The  lead,  prepared  in  a  way  to  present 
as  large  a  surface  as  possible,  by  being  cast  into  rough 
gratings  or  grids,  is  placed  on  pots  over  a  bed  of  spent 
tan-bark,  acetic  acid  being  placed  in  the  pots.  The 
acid  is  slowly  vaporized  by  the  heat  of  the  fermenting 
tan,  and  this,  acting  upon  the  lead,  forms  a  compound  basic 
acetate,  which  undergoes  further  changes  by  the  carbon  di- 
oxide evolved  from  the  fermenting  tan,  and  the  action  of  air 
and  moisture,  finally  resulting  in  the  production  of  white- 
lead  of  commerce  (2PbCO3,Pb(HO)2). 

In  all,  five  oxides  of  lead  are  known,  all  of  which  are 
insoluble  in  water  (Pb2O,  PbO,  Pb2O3,  Pb3O4,  and  PbO2), 
but  of  these  the  PbO  (litharge)  and  the  Pb3O4  (red-lead) 
are  the  more  important. 

Lead  Hydroxide  (2PbO.H2O)  is  produced  in  the  form  of 
a  white,  bulky  precipitate  by  adding  an  alkaline  hydrate 
solution  to  a  solution  of  a  lead  salt. 

Lead  Monoxide  (PbO)  is  formed  by  strongly  heating  the 
metal  in  air,  or  by  roasting  nitrate  or  carbonate  of  lead,  and 
under  the  name  of  litharge  it  is  used  in  the  manufacture  of 
certain  qualities  of  glass  and  pottery,  acid-resisting  cements 
and  lakes,  and  in  connection  with  that  of  oils  and  varnishes. 

Red-Lead  (Minium)  (Pb3O4)  results  from  the  prolonged 
heating  of  the  monoxide  in  contact  with  air  at  about  450°  C., 
and  is  a  scarlet-coloured  powder  which  varies  to  some 
extent  in  colour  and  in  composition  as  prepared  for  com- 
mercial uses,  containing  as  it  does  varying  proportions  of 
other  oxides  of  the  metal.  It  also  occurs  in  natural  deposits, 
and  is  largely  used  in  the  manufacture  of  ceramics,  flint 
glass,  and  as  a  pigment. 


LEAD  AND  ITS  COMPOUNDS  289 

LEAD  (Continued)— 

Lead  Chloride  (PbCl2)  is  a  white,  crystalline  substance 
which  is  precipitated  in  a  curdy  form  from  solutions  of 
lead  salts  by  the  addition  of  hydrochloric  acid,  and  can  be 
obtained  by  dissolving  the  monoxide  or  lead  carbonate 
in  hot  hydrochloric  acid,  from  which  solution  it  crystallizes 
out  on  cooling  in  long  lustrous  needles.  It  is  soluble  in 
boiling  water  (i  part  in  25  parts). 

An  oxychloride  or  a  compound  of  chloride  and  oxide  in  a 
hydrated  condition  known  as  Pattinson's  white -lead  is 
obtained  by  heating  lead  chloride  in  air  and  has  a  com- 
position approximating  to  PbCl.2,PbO,H2O. 

Lead  Sulphate  (PbSO4)  is  a  white,  insoluble  body  resulting 
from  the  precipitation  of  lead  salts  in  solution,  by  sulphuric 
acid  or  solution  of  a  sulphate,  and  is  used  to  some  extent 
in  compounding  paints. 

Lead  Nitrate  (Pb(NO3)2),  a  crystalline  substance  very 
soluble  in  water,  is  made  by  dissolving  litharge  in  nitric  acid, 
and  finds  many  industrial  applications. 

Lead  Iodide  (PbI2)  is  a  beautiful  yellow  insoluble  com- 
pound used  in  bronzing,  mosaic  gold,  printing,  etc. 

Lead  Sulphide  (PbS)  is  a  black  compound  found  native 
as  gakna,  and  can  be  prepared  by  the  action  of  hydrogen 
sulphide  upon  solutions  of  lead  salts.  It  is  insoluble  in 
water,  and  is  used  in  ceramics. 

Lead  Chromate  (PbCrO4)  is  found  in  mineral  form  as 
cvocoisite,  and  is  a  beautiful  chrome-coloured  insoluble  com- 
pound which  finds  use  as  a  pigment. 

Lead  Acetate  (Sugar  of  Lead)  (Pb(C2H3O2)2.3H2O)  is  a 

white,  crystalline,  poisonous  salt,  soluble  in  water,  which 
becomes  anhydrous  when  heated  to  75°  C.,  and  is  made 
by  the  action  of  acetic  acid  on  litharge  (PbO).  It  is  used 
in  dyeing  and  printing  cotton  goods,  in  varnish-making, 
and  in  medicine. 

Commercially  it  is  prepared  in  a  number  of  grades  of 
varying  colour  (white,  grey,  and  brown)  and  purity.  There 
are  other  acetates  —  viz.,  the  monobasic  salt  (Pb2O 
(CH3COO)?)  and  the  tribasic  (Pb(C2H3O2)22PbO.H2O)— 
both  of  which  find  industrial  applications,  the  last  named 
being  used  in  weighting  silk  and  textile  printing. 

Lead  Antimonate  (Naples  Yellow)  is  insoluble  in  water 
and  used  as  a  pigment ;  also  for  staining  glass  and  china 
ware. 

19 


290  LEAD—LEGUMIN 

LEAD  (Continued)— 

Lead  Borate  (Pb(BO2)2H2O)  is  insoluble  in  water  and 
used  in  the  varnish  and  paint  trades  as  a  drier. 

Lead  Carbonate  (PbCO3)  is  a  white,  crystalline  powder, 
insoluble  in  water,  used  in  paint-making. 

Lead  Oleate  (Pb(C18H33O2)2)  is  a  white,  unctuous  sub- 
stance, soluble  in  alcohol,  ether,  benzol,  and  turpentine,  used 
in  making  certain  varnishes  and  lacquers  and  as  a  paint 
drier. 

When  a  lead  solution  is  submitted  to  electrolysis,  the 
metal  is  deposited  in  crystalline  form  at  the  cathode  in 
what  is  commonly  known  as  the  tree  lead. 

All  the  compounds  of  lead  are  poisonous. 

LEAD  ASHES — The  skimmings  due  to  oxidation  in  melting 
down  lead. 

LEAD  PLASTER— A  mixture  of  lead  soaps  of  fatty  acids,  pre- 
pared by  heating  olive  oil  with  litharge  or  by  heating  a 
solution  of  lead  nitrate  with  sodium  linoleate ;  used  in 
medical  practice  as  an  external  application  and  as  a  drier 
in  varnish-making. 

LEATHER — Prepared  from  animal  hides  by  the  action  of 
tannins,  the  process  being  described  as  tanning,  which  is 
effected  by  chemical  combination  of  the  tannin  with  the 
gelatinous  principles  of  the  tissues  employed. 

Artificial  leather  is  the  name  given  to  a  number  of  com- 
posite materials  made  of  any  suitable  base  such  as  cloth, 
felt,  or  paper  coated  with  an  embossed  covering  in  imitation 
of  grained  leather,  pyroxylin  dissolved  in  amyl  acetate 
admixed  with  castor  oil  being  one  of  the  solutions  employed. 
Several  varieties  of  nitrated  cellulose  can  be  used ;  blown 
linseed  and  other  oils  can  be  used  in  place  of  or  in  addition 
to  castor  oil ;  and  a  great  variety  can  be  made  in  the  way 
of  solvents,  whilst  pigments  are  often  introduced  to  give 
colour  and  body  to  the  coverings.  (See  Tanning.) 

LEAVEN  is  really  bread  which  has  commenced  to  decompose 
by  a  sort  of  fermentation,  but  the  use  of  this  stale  bread  for 
leavening  fresh  bread  has  been  superseded  by  the  general 
use  of  yeast. 

LECITHINE — See  Brain  Matter. 

LEGUMIN  (Vegetable  Casein) — The  distinctive  protein  con- 
stituent of  peas,  beans,  and  lentils,  of  nutritive  value  and 
amounting  to  about  25  per  cent,  calculated  on  the  dried 
products.  (See  Albumins  and  Proteins,) 


LEMON  OIL— LIGHT  291 

LEMON  OIL — A  pale  yellow,  limpid  liquid  of  lemon  odour, 
containing  limonene,  pinene,  citral,  and  citronellal,  of  sp. 
gr.  0*858  to  0^859  and  optical  rotation  +60  to  +64,  ex- 
pressed from  the  peel  of  the  Citrus  limonum.  It  is  soluble 
in  alcohol,  ether,  etc.,  and  is  used  in  perfumery,  for  flavour- 
ing, and  in  compounding  some  beverages. 

LEMON  GRASS  OIL— See  Verbena  Oil. 

LENSES — Concave  and  convex  glasses  that  respectively  lessen 
or  enlarge  objects  examined  by  them. 

LENTILS — Seeds  of  the  leguminous  plant  Ervum  lens,  from 
which  a  flour  can  be  prepared. 

LEPIDOLITE  (Lithium  Mica) — A  Moravian  purple  mineral  con- 
taining lithium  and  aluminium  in  combination  as  silicates. 

LEUCINE  (Amino-Caproic  Acid)  (C6H13NO2)— A  decomposi- 
tion product  of  albuminoid  bodies  generally  accompanying 
tyrosine  in  the  animal  economy. 

LEUCITE— A  crystalline  mineral  double  silicate  of  aluminium 
and  potassium  (K.Al(SiO3)2). 

LEVIGATION — The  reduction  of  lumps  and  hard  parts  of 
substances  to  pulverulent  form  by  grinding  in  water  or 
other  liquid. 

LEVULOSE  (C6H12O6) — A  form  of  glucose  which  results  along 
with  dextrose  from  the  action  of  dilute  acids  upon  sucrose 
(cane  sugar).  It  turns  the  plane  of  polarization  of  a  ray  of 
light  to  the  left.  (See  Carbohydrates  and  Saccharoses.) 

LEY — A  solution  of  caustic  soda  or  potash  in  water. 
LIEBIG'S  BULBS— See  Potash  Bulbs. 
LIEBIG'S  CONDENSERS— See  Retort. 

LIGHT — Light  in  nature  is  chiefly  derived  from  the  sun,  but  is 
also  furnished  by  other  heavenly  bodies.  The  glow-worm 
and  the  firefly  have  the  power  of  giving  out  a  light  in  the 
darkness,  and,  as  is  well  known,  decaying  animal  matter 
exhibits  a  pale  phosphorescent  light. 

The  production  of  light  by  animals  is  stated  to  be  due  to 
the  burning  by  oxidation  of  a  substance  named  luciferin  in 
presence  of  a  catalyst  called  lucifemse,  and  the  oxidation 
product  can  be  readily  reduced  again  to  the  original 
substance. 

In  the  case  of  Renilla,  it  is  thought  that  the  phosphor- 
escence produced  at  night  by  stimulation,  is  under  the 
control  of  the  nerve-net  of  the  animal. 


292  LIGHT 

LIGHT  (Continued)— 

The  phosphorescence  of  the  sea  is  light  given  out  by 
countless  bacteria  present  in  the  water. 

When  a  current  of  electricity  is  sent  through  an  electric 
lamp  it  gives  out  light,  because  the  electric  current,  en- 
countering a  resistance  in  its  passage  through  the  filament 
of  the  lamp,  becomes  partially  transformed  into  light. 

Lightning,  as  occurring  in  storms,  is  a  form  of  light  con- 
nected with  electric  discharges  from  the  clouds.  Light  can 
also  be  produced  by  chemical  means,  many  substances, 
such  as  phosphorus,  magnesium,  strontium,  and  sulphur, 
emitting  light  of  different  degrees  and  shades  when  burned 
in  the  air. 

In  the  ordinary  combustion  of  fuel  (wood  and  coal)  light 
is  also  produced ;  in  fact,  combustion  of  organic  matter  is 
always  attended  with  production  of  more  or  less  light  and 
beat,  whilst  flame  has  been  described  as  gas  heated  to  such 
a  temperature  that  it  emits  light  as  well  as  heat. 

Light  can  be  produced  by  the  rubbing  together  of  sugar 
or  quartz,  or  when  quartz  is  rubbed  by  any  material  harder 
than  itself  such  as  topaz  or  sapphire  or  water-worn  pebbles 
of  corundum.  It  is  also  emitted  during  the  act  of  crystalliza- 
tion of  certain  salts  from  their  solutions,  and  exercises  a  con- 
siderable influence  in  respect  of  many  chemical  changes, 
particularly  those  which  take  place  in  animal  and  vegetable 
tissues. 

When  a  stream  of  oxygen  mixed  with  hydrogen  is 
ignited,  the  mixed  gas  burns  without  giving  out  any  sensible 
amount  of  light ;  but  if  the  jet  of  burning  gas  be  directed 
upon  a  piece  of  lime,  the  most  brilliant  light,  or  so-called 
oxyhydrogen  limelight,  is  produced  so  soon  as  the  lime 
becomes  hot. 

We  have  another  familiar  instance  of  the  power  of  solids 
to  influence  the  light  given  out  by  flame  in  the  so-called 
Welsbach  mantle,  in  which  the  burning  gas  (which  in  itself 
would  give  what  is  practically  a  blue  flame  almost  devoid 
of  light)  playing  upon  a  surrounding  mantle  impregnated 
or  charged  with  certain  mineral  oxides,  develops  an  intense 
white  light.  A  mixture  of  thorium  oxide  with  a  small  pro- 
portion of  cerium  oxide  is  commonly  used  in  preparing 
these  mantles.  (See  Gas  Mantles.) 

It  is  difficult  to  answer  the  question,  What  is  light  ?  By 
some  physicists  it  is  regarded  as  essentially  identical  with 
electricity.  It  is  not  so  much  a  thing  as  an  effect,  a  state 
of  matter — that  is  to  say,  illuminated  matter,  varying, 
of  course,  with  the  medium  through  which  it  is  rendered 


LIGHT  293 

LIGHT  (Continued) — 

evident ;  its  revelation  being  dependent  upon  what  are 
called  undulations  or  vibrations  similar  to  those  of  sound 
produced  by  blows  upon  metallic  or  other  bodies  and  by 
musical  instruments.  When  a  gong  is  hit  by  a  hammer, 
it  is  thrown  into  a  state  of  excitement  or  vibration  and 
sound  is  produced ;  and  in  a  similar  sort  of  way,  when  a 
gas  is  ignited  or  when  a  solid  body  (as  in  the  case  of  the 
limelight)  becomes  heated  in  a  flame  of  gas,  light  is  given 
out  in  consequence  of  the  burning  gas  being  thrown  into  a 
state  of  tremendous  excitement  or  vibration.  The  light 
thus  produced  is  quite  distinct  from  the  heat  which  acts  as 
a  first  cause  or  incitement  to  its  production. 

When  a  piece  of  phosphorus  contained  in  a  suitable 
holder  is  placed  within  a  jar  filled  with  oxygen  at  a  tem- 
perature above  34°  C.,  it  takes  fire,  and  emits  a  brilliant 
white  light.  As  the  light  does  not  come  from  without,  it 
must  be  the  result  of  the  chemical  action  that  takes  place 
between  the  phosphorus  and  the  oxygen.  That  being  so,  it, 
or  something  that  furnishes  it,  must  be  contained  or  locked 
up  in  the  one  or  other,  or  both,  of  these  substances,  as 
explained  in  the  section  on  Force  (p.  205).  As  a  matter  of 
fact,  heat  always  accompanies  light,  as  in  the  case  of  the 
sun's  rays. 

Light  travels  at  a  very  great  rate — about  185,157  miles 
in  a  second — and  is  only  eight  minutes  in  coming  from  the 
sun  to  the  earth. 

It  has  been  recently  demonstrated  by  experiment  that 
speech  can  be  transmitted  by  the  agency  of  light. 

Light  is  reflected  when  its  rays  fall  upon  a  mirror — that 
is  to  say,  it  is  thrown  back  at  an  angle — and  may  be  thus 
made  to  show  a  brilliant  spot  upon  a  wall.  White  light 
is  said  to  be  made  up  principally  of  seven  colours — viz., 
violet,  indigo,  blue,  green,  yellow,  orange,  and  red ;  and  if 
a  circular  piece  of  cardboard  be  painted  with  these  seven 
colours  in  equal  sections  and  made  to  rotate,  or  spin 
quickly,  the  several  colours  disappear  to  the  eye,  and  the 
whole  face  of  the  disc  appears  to  be  white. 

The  green  parts  of  plants  absorb  carbon  dioxide  gas 
from  the  atmosphere  under  the  influence  of  solar  light, 
the  carbon  being  assimilated  or  fixed  in  their  tissues  by 
chemical  changes,  oxygen  being  at  the  same  time  restored 
to  the  atmosphere  ;  this  change  materially  assists  in  pre- 
serving the  uniformity  of  composition  of  the  air.  These 
changes,  however,  do  not  take  place  when  the  light  is 
excluded.  Vegetable  matter  cannot  make  its  green  colour- 


294  LIGHT— LIGNIN 

LIGHT  (Continued)— 

ing-matter  (chlorophyll)  without  light,  and  so  celery,  sea- 
kale,  etc.,  are  grown  in  a  blanched  state  by  being  kept  in 
the  dark. 

A  mixture  of  chlorine  gas  with  hydrogen  gas  in  certain 
proportions,  undergoes  no  chemical  change  in  the  dark,  but 
if  exposed  to  sunlight,  the  two  gases  enter  into  combination 
with  explosive  violence. 

Again,  the  art  of  photography  depends  upon  chemical 
changes  brought  about  on  the  prepared  (sensitized)  paper  or 
plate  by  the  direct  action  of  light  upon  chemicals  placed  on 
their  surfaces  ;  solar  light  having  the  power  of  causing  de- 
composition of  the  oxide,  chloride,  nitrate,  or  bromide  of 
silver,  for  example,  when  these  substances  (with  which 
their  surfaces  are  variously  prepared)  are  exposed  to  it 
under  certain  conditions. 

The  bleaching  of  linen  and  other  goods  by  exposing 
them  to  moisture  and  air  is  another  well-known  illustration 
of  the  influence  of  light  in  effecting  chemical  changes. 

Many  chemical  reactions  are  accelerated  by  light,  and 
these  effects  are  more  marked  in  the  presence  of  ultra- 
violet light  than  in  the  presence  of  light  of  shorter  wave 
length.  Radiant  heat,  light,  and  electricity  are  similar 
from  a  purely  physical  standpoint  and  they  produce  similar 
chemical  changes.  (See  also  Polarization.) 

LIGHTNING— See  Electricity  and  Light. 
LIGHT  OIL— See  Coal. 

LIGNIN — A  constituent  of  wood,  said  to  be  composed  of  two 
substances  of  undetermined  constitution  and  formulae  (but 
represented  as  C40H40On  and  C54H48O18)  resulting  from 
the  treatment  of  wood  with  70  per  cent,  sulphuric  acid.  A 
better  result  is  stated  to  be  obtained  by  first  of  all  saturat- 
ing the  powdered  wood  with  a  mixture  of  acetone  and 
ethylic  alcohol  and  treating  the  product  with  strong  hydro- 
chloric acid.  The  cellulose  and  other  carbohydrates  are 
dissolved  and  the  lignin  is  left  behind,  amounting  to  some 
28  per  cent,  of  the  (pine)  wood,  representing  the  micro- 
scopic structure  of  the  wood  cells.  It  is  almost  completely 
dissolved  by  digestion  in  5  per  cent,  caustic  soda  solution 
at  170°  C.,  and  yields  lignic  acids  by  fusion  with  caustic 
potash. 

Lignin  is  supposed  to  result  from  changes  in  the  cellu- 
lose forming  originally  the  walls  of  the  living  cells  of  wood, 
so  that  the  heart  of  a  tree  is  composed  largely  of  lignin  as 
distinct  from  the  soft,  pithy  living  parts. 


LlGNlTE-LlMOtilTE  i$$ 

LIGNITE— A  brownish-black  natural  deposit  allied  to  coal, 
found  in  many  parts  of  the  world,  which  yields  so-called 
paraffin  oil  upon  distillation.  It  contains  from  27  to  43 
per  cent,  of  carbon,  and  its  calorific  value  is  about  half 
that  of  coal.  The  deposits  in  Holland  and  Italy  have 
been  largely  worked  since  1917. 

A  recent  examination  of  lignite  from  the  Riebeck  Montan 
Works  yielded  15  per  cent,  of  a  quality  of  bitumen  which 
was  soluble  in  hot  benzene  and  8  per  cent,  of  another 
quality  which  was  dissolved  at  a  higher  temperature,  a 
large  part  of  the  extractives  being  identical  in  composition 
with  so-called  Montan  wax. 

The  insoluble  part  yields  the  major  portion  in  a  soluble 
form  on  heating  with  alkali  in  solution,  as  so-called  "  humic 
acids"  which  are  precipitable  upon  acidification  of  the 
alkaline  extract.  (See  Montan  Wax.) 

LIGNUM  VIT-ffl — The  wood  of  Guaiacum  officinale  or  of  Guaiacum 
sanctum.  It  is  employed  to  some  extent  in  the  form  of 
shavings,  raspings,  and  sawdust  for  the  making  of  decoc- 
tions, and  more  extensively  for  making  taps  and  vessels, 
being  hard,  strong  and  capable  of  withstanding  the  action 
of  many  liquids  better  than  ordinary  wood. 

LIME— See  Calcium. 

LIME  (CHLORIDE  OF)— See  Calcium. 
LIMELIGHT— See  Light. 

LIMES  (OIL  OF) — The  essential  oil  of  the  rind  of  Citrus 
limetta  containing  citral  and  limonene ;  sp.  gr.,  0*882 ; 
optical  rotation,  4-35  to  +40;  and  refractive  index,  1*484 
to  1*485.  It  is  soluble  in  alcohol,  ether,  etc.,  and  used  as 
a  flavouring  material  and  in  perfumery,  confectionery,  etc. 

LIMESTONE— See  Calcium. 

LIMONENE — Dextro-limonene  (hesperidene,  citrene,  or  car- 
vene).  The  oil  of  orange  rind  consists  almost  entirely  of 
this  terpene,  which  is  also  a  constituent  of  carvene,  dill  oil, 
and  citron  oil.  It  boils  at  175°  C. 

Lsevo  limonene  is  present  to  some  extent  in  the  oil  of 
fir-cones,  associated  with  other  terpenes. 

Dipentene  is  inactive  limonene. 

LIMONITE — A  mineral  hydrated  iron  oxide — bog  iron  ores 
(2Fe203.3H20). 


296  LIMPID— LINSEED  OIL 

LIMPID — Clear  and  transparent  fluids,  the  particles  of  which 
exhibit  great  mobility  or  rapidity  of  movement. 

LINALOE  OIL— A  Mexican  distilled  wood  oil  of  colourless, 
fragrant  character,  containing  linalool  and  geraniol,  having 
a  sp.  gr.  of  from  0-875  to  0*890,  soluble  in  alcohol  and 
ether,  and  used  in  perfumery. 

LINALOOL  (C10H18O)— A  liquid  of  boiling-point  195°  C., 
isomeric  with  geraniol,  occurring  as  linalyl  acetate  in  the 
cacao-bean  and  the  oils  of  lavender,  coriander,  neroli,  and 
sage. 

LINARITE — A  crystalline,  basic,  cuprous  lead  sulphate  mineral 
(PbS04,CuH202). 

LINEN — Cloth  manufactured  from  the  fibres  of  the  flax 
stem. 

LINOLEIC  ACID  (C17H31.COOH)  occurs  as  a  glyceride  in 
linseed,  poppy,  hempseed,  and  other  drying  oils,  and  as  a 
constituent  of  some  non-drying  oils.  (See  Linseed  Oil.) 

LINOLENIC  ACID  (C18H30O2)  occurs  as  a  glyceride  in  linseed, 
hempseed,  and  some  other  drying  oils,  and  is  very  oxidiz- 
able.  (See  Linseed  Oil.) 

LINSEED  OIL  is  expressed  by  pressure  from  flax  seed  (Linum 
usitatissimum),  and  is  largely  used  in  making  paints,  varnishes, 
linoleum,  patent-leather  lacquers,  rubber  substitutes,  and 
soft  soaps,  while  the  residual  cake  is  used  for  feeding 
cattle. 

The  cake  is  known  to  contain  hydrocyanic  acid  derived 
from  a  contained  glucoside,  but  most  of  it  is  dissipated 
during  the  maceration  of  the  seeds  and  by  evaporation. 

Linseed  oil  has  a  sp.  gr.  of  0-932  to  0-938,  a  saponi- 
fication  value  of  185  to  195,  and  iodine  value  171  to  200. 
It  contains  linoleic  (linolic)  acid  (C18H32O2)  in  combination 
with  glycerine  and  is  typical  of  the  class  of  so-called  "  dry- 
ing oils,"  from  their  readiness  to  absorb  oxygen  upon 
exposure  to  the  air,  being  changed  thereby  into  a  trans- 
parent, sticky  mass.  Linolenic  acid  (C18H30O2)  is  said 
to  accompany  the  linoleic  acid  as  a  constituent  of  the 
oil.  A  published  description  of  linseed  oil  is  to  the 
effect  that  it  consists  of  85  to  90  per  cent,  liquid  glycer- 
ides,  containing  about  5  per  cent,  oleic  acid,  15  per  cent, 
linolic  acid,  15  per  cent,  linolenic  acid,  and  65  per  cent, 
isolinolenic  acid,  the  remaining  10  to  15  per  cent,  being 
made  up  of  glycerides  of  solid  fatty  acids,  chiefly  palmitic. 

When  first  expressed,  the  oil  is  pale  yellow  and  not  dis- 


LINSEED  OIL— LITHIUM  297 

LINSEED  OIL  (Continued} — 

agreeable  in  smell,  but  unless  it  is  refined  it  quickly  turns 
rancid,  dark  in  colour,  and  repulsive  in  odour.  It  is 
soluble  in  alcohol,  chloroform,  carbon  disulphide,  benzol, 
and  turpentine.  H eating  alone,  under  pressure,  at  a  constant 
temperature  greatly  increases  the  viscosity  and  the  iodine 
value  decreases,  while  the  saponification  value  remains 
unchanged.  When  boiled  until  it  loses  one-eighth  of 
its  weight,  it  thickens,  becomes  viscid,  and  dries  quickly 
upon  exposure  to  air.  The  oxidation  of  linseed  oil  by  a 
current  of  air  is  facilitated  by  the  use  of  a  little  manganese 
dioxide  or  other  drier,  and  this  process  gives  "  body  "  and 
drying  properties  to  the  product.  Saponified  with  alkalies, 
linseed  oil  gives  soft  soap  of  a  thin  character. 

Supplies  come  from  many  places,  and  Argentine  has 
about  3,500,000  acres  of  flax  under  cultivation.  Linseed 
yields  by  pressure  aided  with  heat,  about  27  per  cent,  of 
linseed  oil.  (See  Paints  and  Varnishes.) 

LIPASE— See  Enzymes. 

LIQUATION — The  stage  reached,  when  heating  an  ore  or 
other  metallic  mixture  containing  ingredients  differing 
sensibly  in  fusibility,  at  which  the  most  fusible  constituent 
melts  and  flows  away  from  the  mass. 

LIQUID AMBAR  (Storax) — An  amber-yellow,  thick  oil  or  balsam 
produced  from  incisions  made  in  a  tree  (Liquidambav  styraci- 
folia)  which  grows  in  Louisiana,  Florida,  and  Mexico.  It  is 
soluble  in  hot  alcohol  and  ether,  and  is  used  in  perfumery. 
(See  Balsams.) 

LIQUOR  AMMONITE — A  strong  solution  containing  35  per 
cent,  of  ammonia  gas  dissolved  in  water,  having  a  sp.  gr. 
of  0-882  at  15°  C. 

LIQUORICE  JUICE,  as  obtained  from  the  roots  of  the  Gly- 
cyrrhiza  glabra  and  Gl.  echinata,  contains  a  sweet,  amorphous 
substance,  soluble  in  alcohol  and  hot  water,  named  gly- 
cyvrhizin  (C24H3CO2),  which  is  said  to  yield  glucose  when 
boiled  with  dilute  sulphuric  acid. 

Spanish  liquorice  is  used  as  a  demulcent  remedy  for 
coughs,  etc. 

LITHARGE— See  Lead. 

LITHIUM  (Li) — Atomic  weight,  7 ;  sp.  gr.,  0-59  ;  melting- 
point,  1 80°  C.  Lithium  is  a  somewhat  rare  element  found 
in  small  quantities  widely  distributed  in  nature,  in  asso- 


298  LITHIUM— LITMUS  SOLUTION 

LITHIUM  (Continued)— 

ciation  with  certain  more  or  less  rare  minerals,  including 
petalite,  spodumene,  and  lepidolite  (lithium  mica),  all  of  which 
are,  in  the  main,  silicates  of  aluminium.  It  is  also  found 
in  several  mineral  waters  which  are  extensively  used  for 
medicinal  purposes. 

Lithium  in  the  metallic  form  is  the  lightest  known  solid 
substance,  and  is  obtained  from  the  fused  chloride  by 
electrolysis ;  it  is  of  a  soft  character,  and  has  a  silver-like 
appearance,  but  quickly  tarnishes  when  exposed  to  the 
air,  so  that  it  has  to  be  kept  in  naphtha  or  kerosine.  Like 
sodium  it  decomposes  water  at  the  ordinary  temperature, 
lithium  hydroxide  being  formed  and  passing  into  solution, 
whilst  hydrogen  gas  is  generated. 

Lithium  oxide  (Li2O)  exhibits  alkaline  properties,  and, 
in  common  with  the  carbonate,  is  used  medicinally  as  an 
antidote  to  gouty  complaints. 

The  volatile  lithium  salts  give  a  crimson  tinge  to  flame. 
The  following  lithium  compounds  are  among  those  best 
known :  hydroxide  (LiHO),  carbonate  (Li2CO3)  (only 
slightly  soluble  in  water),  chloride  (LiCl),  and  phosphate 
(Li3P04). 

The  hydroxide,  chloride,  bromide,  citrate,  and  iodide  are 
all  soluble  in  water,  the  four  last  named  being  all  used  in 
medicine.  The  carbonate,  citrate,  and  iodide  are  also  used 
in  compounding  mineral  water,  whilst  the  fluophosphate 
and  the  fluoride  are  used  in  ceramics  and  enamels. 

LITHOPONE — A  white  paint  pigment  having  zinc  sulphide, 
zinc  oxide,  and  barium  sulphate  as  chief  basic  constituents, 
prepared  by  strongly  heating  a  mixture  of  zinc  sulphide 
and  barium  sulphate,  or  one  of  barium  sulphide  and  zinc 
sulphate,  to  redness. 

LITMUS — A  violet-blue  colouring  matter  prepared  from  the 
lichens  Lecanora  tavtarea  and  Rocella  tinctoria  by  treatment 
with  ammonia  and  potash,  and  then  fermenting  the  mass. 

LITMUS  PAPER  is  absorbent  filter  or  blotting  paper  stained 
by  soaking  (and  subsequent  drying)  in  a  solution  of  litmus. 
Acid  solutions  turn  this  blue  into  red,  and  alkaline  solutions 
restore  the  blue  colour,  so  it  is  commonly  used  to  determine 
the  alkaline  or  acid  nature  of  liquids.  Litmus  paper  can 
be  prepared  of  a  neutral  tint  equally  amenable  to  both 
reactions.  (See  Turmeric  Paper  and  Volumetric  Analyses.) 

LITMUS  SOLUTION  may  be  used  for  the  same  purposes  as 
litmus  paper. 


LIVER  OF  SULPHUR— LUBRICANTS  299 

LIVER  OF  SULPHUR— An  old  name  still  used  commercially 
in  respect  of  a  mixture  of  potassium  sulphides  as  prepared 
by  heating  sulphur  and  potassium  carbonate  in  a  closed 
vessel. 

LIXIVIATE — To  extract,  by  solution,  alkaline  substances  from 
materials  containing  them,  such  as  black  ash — that  is,  crude 
sodium  carbonate.  (See  Sodium.) 

LOADSTONE — Magnetic  ironstone.  (See  Iron  and  Elec- 
tricity.) 

LOAM — Clay  more  or  less  mixed  with  sand  or  marl. 

LODE — A  vein  or  fissure  in  rocks  filled  with  metalliferous 
deposit. 

LOGWOOD  EXTRACT  is  made  from  the  wood  of  a  tree 
(Hamatoxylum  campechianum)  which  grows  in  Central 
America  and  the  West  Indies,  and  yields  its  fine  red  colour 
both  to  water  and  alcohol — the  latter  more  readily.  The 
colour  left  to  itself  turns  yellowish  and  subsequently  black. 
It  is  turned  yellow  by  acids,  while  alkalies  deepen  it  and 
give  it  a  more  purple  hue.  A  blue  colour  can  also  be 
obtained  from  it  by  mixing  with  verdigris. 

It  is  chiefly  used  for  black  colours,  to  which  it  imparts 
great  lustre,  but  it  is  also  extensively  used  in  compounding 
various  colours  on  cloth  and  other  stuffs. 

LUBRICANTS — Preparations  used  to  decrease  the  friction 
between  opposed  solid  faces,  which  arises,  as  is  sup- 
posed by  some,  from  true  cohesion.  The  solid  varieties 
include  natural  and  artificial  graphite,  talc,  mica,  and  other 
substances,  such  as  "flowers  of  sulphur"  and  white-lead, 
which  are  used  for  curing  hot  bearings. 

The  natural  graphite  is  usually  of  the  so-called  flake 
variety,  and  varies  in  size  of  particles  from  ^  in.  and 
less  than  ^^  in.,  whilst  the  artificially  produced  kind  is 
amorphous,  and  ground  even  finer  than  the  natural  product. 
The  latter  is  sold  under  the  trade  names  of  "  Aquadag  " 
and  "  Hydrosol  "  when  in  admixture  with  water,  and  as 
"  Oildag,"  "  Oleosol,"  and  "  Kollag  "  when  in  admixture 
with  oil. 

Generally  speaking,  solid  lubricants  are  applied  dry  in 
cases  where  for  special  reasons  it  is  inadvisable  or  not 
possible  to  use  liquid  or  semisolid  lubricants,  although 
they  are  usually  employed  in  admixture  with  oil  or  as 
ingredients  in  greases. 

"  Aquadag  "  used  as  a  cylinder  lubricant  has  been  found 
advantageous  where  solid  friction  occurs,  as  in  worm-gear, 


300  LUBRICANTS— LYMPH 

LUBRICANTS  (Continued)— 

although  equally  good  results  have  been  obtained  by  the 
use  of  natural  flake  graphite ;  and  it  has  been  concluded 
that  the  lubricating  value  of  graphite  depends  upon  its 
chemical  purity. 

The  lubricating  value  of  oil  depends  upon  something  not 
yet  properly  understood ;  it  is  not  viscosity.  What,  how- 
ever, is  required  in  a  liquid  lubricant  is  that  it  shall 
penetrate  into  the  narrow  spaces  between  journal  and 
bearing,  thus  "wetting"  or  spreading  over  the  surfaces 
which  are  in  motion  together. 

The  function  of  a  lubricant  is  to  keep  metal  surfaces 
separate  with  a  minimum  expenditure  of  energy.  Vegetable 
and  animal  oils  possess  greater  value  than  mineral  oils 
obtained  from  crude  petroleum  and  coal  tar,  which  are 
also  used  as  lubricants  in  common  with  the  so-called  rosin 
oil,  obtained  by  the  destructive  distillation  of  resin.  They 
are  generally  graded  in  accordance  with  their  specific 
gravities  and  viscosities. 

The  so-called  "germ  process"  of  lubrication  employs 
one  or  more  fatty  acids  with  mineral  oil  as  the  instrument 
of  lubrication,  i  or  2  per  cent,  being  incorporated  according 
to  chemical  circumstances.  This  is  said  to  reduce  the 
coefficient  of  friction  from  0-0084  to  0-0052 — that  is,  some 
25  per  cent,  on  a  friction-testing  machine. 

Oils  exhibit  a  rapid  increase  in  viscosity  with  pressure, 
this  increase  being  much  greater  for  the  mineral  than  for 
animal  and  vegetable  oils. 

LUMBANG  OIL— See  Candle-nut  Oil. 

LUMINOSITY— See  Light  and  Flame. 

LUMINOUS  PAINT — See  Calcium  Compounds  and  Paints. 

LUNAR  CAUSTIC— Fused  silver  nitrate.     (See  Silver.) 

LUPULIN— See  Hop. 

LUTECIUM  (Lu)— Atomic  weight,  175.  One  of  the  extremely 
rare,  recently  discovered  elements  of  the  yttrium  group. 

LUTES — Cements  used  to  pack  or  seal  the  joints  of  vessels, 
varying  in  nature  according  to  the  chemicals  concerned. 

LYE  (LEY) — A  solution  of  alkali  such  as  used  in  soap- 
making. 

LYMPH  may  be  regarded  as  transuded  serum  of  blood  which 
has  been  reabsorbed  from  the  tissues  and  carried  back  to 
the  circulation  by  the  lymphatics.  It  is  alkaline,  contains 


LYMPH— MA  GNESWM  301 

LYMPH  (Continued)— 

about  5  per  cent,  solid  constituents  made  up  of  plasma  and 
white  corpuscles,  and  is  really  diluted  blood-serum,  from 
which  the  tissues  have  taken  up  what  they  require  for 
nourishment. 

"  LYSOL  " — The  name  of  a  cresolic  antiseptic  prepared  so  as 
to  be  miscible  with  water,  making  a  clear  solution. 

MACE — The  arillus  or  envelope  of  the  shell  of  the  fruit  of 
the  nutmeg  (Myvistica  moschata),  cultivated  in  the  Molucca 
Islands  and  the  tropics  (East  Indies,  India,  etc.),  containing 
two  varieties  of  essential  oil.  The  seeds  also  yield  a 
volatile  essential  oil,  which  forms  a  soapy  mass  with 
alkalies,  but  these  oils  are  not  to  be  confused  with  the 
fixed  oil  or  butter  called  myristin  which  is  expressed  from 
the  seeds.  Mace  is  used  as  a  condiment  in  cooking,  having 
a  more  agreeable  odour  than  nutmeg. 

MACE  OIL — A  colourless  or  slightly  yellow  oil  of  aromatic 
odour,  containing  pinene,  dipentene,  etc. ;  of  sp.  gr.  0*91 
to  0-93,  and  optical  rotation  +  10.  It  is  soluble  in  alcohol, 
ether,  etc.,  and  is  used  in  flavouring. 

MADDER  (Turkey  Red) — The  pulverized  root  of  Rubia  tinctovia, 
an  herbaceous  perennial,  which  is  cultivated  in  the  Levant, 
France,  and  Holland,  and  grows  best  in  warm  climates. 
It  contains  a  glucoside  which  yields  by  fermentation  the 
beautiful  red  dye  known  as  alizarin.  It  also  contains  pur- 
purin.  (See  Alizarin.) 

MAGENTA  or  FUCHSINE — An  aniline  dye,  being  a  compound 
of  rosaniline  with  an  acid,  prepared  by  heating  a  mixture 
of  nitro-benzene,  aniline,  and  toluidine  with  iron  filings  and 
hydrochloric  acid.  It  dyes  silk  and  wool  direct.  (See 
Trimethy  Imethane. ) 

MAGMA— A  thin  paste. 

MAGNESIA — See  Magnesium  Compounds. 

MAGNESITE — See  Magnesium. 

MAGNESIUM  (Mg)  and  its  Compounds— Atomic  weight,  24 ; 
sp.  gr.,  1*74;  melting-point,  651°  C.  Magnesium  is  not 
found  uncombined  in  nature,  but  exists  abundantly  in  com- 
bination associated  with  calcium  as  a  double  carbonate  in 
the  form  of  the  mineral  dolomite. 

Magnesite  or  Greekstone  is  essentially  magnesium  car- 
bonate, and  in  some  forms  is  nearly  pure  (MgCO3), 
large  deposits  of  which  are  found  in  Greece,  Austria- 


302  MAGNESIUM  AND  ITS  COMPOUNDS 

MAGNESIUM  (Continued)— 

Hungary,  and  other  countries.  It  is  extensively  used  for 
making  refractory  bricks.  Kieserite  is  magnesium  sulphate 
(MgSO4,H2O)  and  cavnallite  is  a  double  chloride  of  mag- 
nesium and  potassium  (MgCl2.KC1.6H2O),  from  which 
substance  in  a  fused  state,  magnesium  in  a  metallic  form  is 
chiefly  produced  by  electrolysis. 

It  has  been  seriously  proposed  to  extract  the  metal  from 
the  magnesium  salts  contained  in  seawater  in  Norway, 
where  water-power  is  readily  available. 

Magnesium  is  a  silver-white  metal  which  tarnishes 
slightly  upon  exposure  to  the  air,  and  readily  takes  fire 
when  heated  in  the  air,  combining  with  the  oxygen  thereof 
and  forming  magnesium  oxide  (MgO).  This  burning  is 
attended  with  a  brilliant  white  light  often  used  for  photo- 
graphic purposes.  It  is  used  in  pyrotechnics  and  in  making 
some  alloys. 

The  metal  is  35  per  cent,  lighter  than  aluminium,  and 
has  a  tensile  strength  about  twice  of  that  metal.  An 
alloy  with  80  per  cent,  magnesium  has  been  found  to 
be  possessed  of  excellent  qualities  for  use  in  the  construc- 
tion of  motors  for  aeroplanes,  automobiles,  and  electric 
tramcars. 

The  addition  of  as  little  as  0-5  per  cent,  magnesium  to 
many  alloys,  such  as  those  of  aluminium  and  copper,  and 
copper  and  zinc,  results  in  a  remarkable  age-hardening 
after  quenching,  said  to  be  analogous  to  the  hardening  and 
tempering  of  steel. 

Acted  upon  by  dilute  acids,  hydrogen  is  evolved  and 
the  corresponding  salts  of  magnesium  are  produced  in 
solution. 

The  Oxide  (MgO)  occurs  in  nature  in  the  mineral  periclase, 
and  is  produced  in  the  form  of  calcined  magnesia  when  mag- 
nesium carbonate  is  subjected  to  a  sustained  heat.  The 
product,  which  is  white  and  light,  is  used  as  a  cement 
owing  to  its  double  capacity  of  slowly  absorbing  carbon 
dioxide  and  moisture,  also  for  heat  insulating  and,  owing 
to  its  refractory  character,  is  of  peculiar  value  for  the 
manufacture  of  crucibles  and  cupels  for  metallurgical 
purposes. 

Magnesium  Sulphate  or  Epsom  Salts  (MgSO47H2O)  is 
readily  obtained  by  the  action  of  sulphuric  acid  upon  dolomite 
and  separation  of  the  insoluble  calcium  sulphate  which  is 
simultaneously  formed.  It  is  a  colourless,  crystalline  salt, 
soluble  in  water,  used  as  a  medicine,  in  fireproofing, 


MAGNESIUM— MAIZE  OIL  303 

MAGNESIUM  (Continued)— 

and  warp  sizing  cotton  goods.    It  is  also  of  value  as  a 
fertilizer. 

Magnesia  Alba,  of  the  pharmacists,  is  a  varying  mixture 
of  magnesium  carbonate  and  hydroxide,  made  by  pre- 
cipitating a  boiling  solution  of  magnesium  sulphate  with 
a  hot  solution  of  sodium  carbonate.  It  is  used  in  fire- 
proofing  and  as  a  face-powder,  etc. 

Magnesium  Chloride  is  a  deliquescent  body  very  soluble 
in  water,  which  can  be  obtained  in  crystalline  form 
(MgCl26H2O)  as  also  in  the  anhydrous  state  (MgCl2).  It 
loses  two  molecules  of  water  at  100°  C.,  and  is  used  for 
dressing  cotton  fabrics,  fireproofing  wood,  etc. 

Magnesium  Carbonate  (MgCO3),  which  can  be  prepared 
by  adding  sodium  carbonate  solution  to  one  of  magnesium 
sulphate,  is  a  light,  white,  amorphous  substance  used  in 
common  with  natural  deposits  of  the  carbonate  in  fire- 
proofing,  making  tooth-powders,  and  for  preventing  the 
formation  of  scale  in  boilers. 

Magnesium  Citrate  (Mg3(C6H5O7)2.i4H2O)  is  a  soluble, 
white  salt  used  in  medicine. 

Magnesium  Hydroxide  (Mg(OH)2)  is  a  white  powder 
obtained  by  precipitation  from  a  soluble  magnesium  salt  by 
a  solution  of  sodium  hydrate,  and  is  used  in  sugar-refining. 

Magnesium  Nitrate  (Mg(NO3)26H2O)  is  a  white,  crystal- 
line salt,  soluble  in  water,  used  in  pyrotechnics. 

Magnesium  Fluoride  (MgF2)  is  a  white,  crystalline  com- 
pound used  in  ceramics. 

MAGNET— See  Electricity. 

MAGNETIC  IRON  ORE  (Loadstone) — A  native,  crystalline 
compound — ferroso-ferric  oxide  (Fe3O4) — having  magnetic 
properties. 

MAGNETISM— See  Electricity. 

MAGNETITE— Magnetic  iron  ore  or  loadstone  (Fe3O4)  found 
in  the  United  States  of  America  and  elsewhere. 

MAIZE  OIL — The  germs  of  the  maize  plant  (Zea  Mays .  L.) 
yield  about  12  per  cent,  of  corn  oil,  constituting  a  by- 
product in  the  preparation  of  maize  starch.  It  is  golden 
yellow  in  colour,  and  is  composed  chiefly  of  the  glycerides 
of  oleic,  linolic,  and  palmitic  acids.  Its  sp.  gr.  is  0-920 
to  0-923,  refractive  index  1-4730  to  1*4735,  saponification 
value  1 88  to  193,  and  iodine  value  in  to  123. 


304  MAIZE  OIL—MALTASE 

MAIZE  OIL  (Continued)— 

It  is  an  edible  oil,  and  is  also  used  for  lubricating  and 
leather-dressing,  etc. 

MALACHITE — Native  basic  copper  carbonate  (CuCO3  + 
CuO2H2).  (See  Copper.) 

MALACHITE  QUEEN — An  organic  dye.  (See  Dimethylani- 
line.) 

MALE  FERN  OIL — A  nearly  colourless  oil  containing  hexyl 
and  octyl  esters  of  fatty  acids,  distilled  from  the  rhizome  of 
Dryopteris  filix-mas  marginalis.  It  has  a  sp.  gr.  of  0-85,  is 
soluble  in  alcohol  and  ether,  is  used  in  medicine,  and 
stated  also  to  be  used  in  compounding  some  varieties  of  gin 
and  certain  other  liquors. 

MALIC  ACID  (C4HLO5)  occurs  together  with  citric  acid  in 
unripe  apples  and  in  many  other  fruits,  including  goose- 
berries, cherries,  bilberries,  strawberries,  mountain-ash 
berries,  quinces,  etc. ;  also  in  the  roots  and  flowers  of  many 
plants.  A  concentrated  syrup  left  to  evaporate,  yields  the 
acid  in  the  form  of  colourless,  odourless,  and  deliquescent 
needles  or  prisms,  which  melt  at  100°  C.,  and  are  soluble  in 
water.  Maple  sap  contains  calcium  malate.  The  malates 
are  soluble  in  water. 

MALLEABILITY — Admitting  of  being  hammered  out  into  thin 
sheets.  (See  Metals.) 

MALLET  BARK — The  bark  of  Eucalyptus  occidental^  of 
Queensland,  containing  about  from  30  to  50  per  cent, 
tannin;  there  is  a  commercial  extract  of  22  to  24°  B., 
containing  from  30  to  36  per  cent,  tannin. 

MALONIC  ACID  (C3H4O4)  is  said  to  be  contained  in  beetroot 
in  combination  with  calcium,  and  may  be  prepared  by  the 
oxidation  of  malic  acid.  It  crystallizes  in  white  plates 
which  are  soluble  in  water  and  alcohol  and  melts  at 
132°  C. 

MALT — Barley  or  other  grain,  the  starch  of  which  has  been 
converted  into  malt  sugar  by  the  enzyme  diastase  during 
germination  in  the  process  known  as  malting.  Malt  sugar 
(maltose,  C^H^O^HgO)  is  a  hard,  crystalline  body  of 
little  sweetness,  very  similar  to  grape  sugar,  and  strongly 
dextro-rotatory.  The  maltose  is  in  turn  converted  by 
another  ferment  (maltase)  into  grape  sugar  (C6HJ3O6). 

MALTASE— See  Malt, 


MA  LTING—MA  NGA  NESE  305 

MALTING — The  preparation  of  barley  or  other  grain  by 
germination  ready  for  brewing.  (See  Beer.) 

MALTOSE— See  Malt. 

MANDARIN  OIL— A  yellow  oil  of  sp.  gr.  about  0-85  and 
optical  rotation  +  70°,  expressed  from  the  peel  of  the 
mandarin  orange  (Citrus  bigavadia  sinensis).  It  contains 
limonene,  citral,  etc.,  is  soluble  in  alcohol  and  ether,  and  is 
used  in  perfumery,  medicine,  and  for  flavouring  purposes. 

MANGANATES — See  Manganese  Compounds. 

MANGANESE  (Mn)  and  its  Compounds — Atomic  weight,  55 ; 
sp.  gr.,  8;  melting-point,  1,230°  C.  Manganese  is  found  in 
nature  chiefly  in  the  form  of  pyrolusite — a  black  oxide 
(MnO2).  There  are  two  other  native  oxides — viz.,  braunite 
(Mn2O3)  and  hausmannite  (Mn3O4) — while  manganite  is  a 
hydrated  oxide  (Mn2O3H2O) ;  manganese  spar  is  carbonate 
(MnCO3)  and  manganese  blende  is  native  sulphide  (MnS). 
Manganiferous  deposits  occur  abundantly  in  various  parts 
of  the  world,  including  the  United  States  of  America, 
Canada,  India,  Brazil,  Russia,  and  Cuba. 

Metallic  manganese  can  be  obtained  by  reduction  of  the 
oxide,  using  carbon  in  an  electrical  furnace,  but  is  com- 
mercially prepared  by  using  powdered  aluminium  for  re- 
duction of  the  oxide  in  a  refractory  furnace,  the  mixture 
being  ignited  by  means  of  a  fuse.  When  required  in  a 
purer  state,  fused  anhydrous  manganese  chloride  is  reduced 
by  heating  with  metallic  magnesium.  It  is  of  a  reddish- 
grey  colour,  is  soluble  in  dilute  acids,  and  is  extensively 
used  in  the  metallic  state,  as  a  hardener  of  steel  as  made 
for  certain  special  applications.  An  alloy  of  manganese 
and  boron  is  used  in  making  varieties  of  bronze,  brass,  and 
other  alloys. 

Manganese  ore — the  black  oxide — is  largely  used  in  the 
manufacture  of  chlorine  by  the  action  of  hydrochloric  acid, 
the  chlorine  in  turn  being  used  for  the  manufacture  of 
bleaching  powder  (chloride  of  lime).  (See  Chlorine  and 
Alkali  Trade.) 

Oxides  of  Manganese — Of  these  the  most  important 
members  are  represented  by  the  formulae  MnO,  Mn3O4, 
Mn2O3,  and  MnO2,  and  the  latter  combines  with  some  other 
oxides — including  calcium  combinations — forming  unstable 
compounds,  supposed  to  be  represented  by  the  formulas 
CaO,MnO2,  CaCteMnO,  and  CaO,5MnO2,  the  manganese 
oxides  acting  the  part  of  weak  acids. 

Manganese  Dioxide  (MnO2)  can  be  prepared  by  adding  a 

20 


3o6  MANGANESE  AND  ITS  COMPOUNDS 

MANGANESE  (Continued)— 

solution  of  bleaching  powder  to  a  manganous  solution  or 
by  roasting  the  monoxide  in  oxygen,  and  when  dried  and 
heated  to  redness  it  decomposes,  becoming  reduced  to  a 
lower  oxide  and  giving  off  oxygen  gas,  thus  : 


=  Mn3O4+O2. 

It  is  largely  employed  in  the  manufacture  of  chlorine  and  as 
an  oxidizing  agent. 

Manganese  Hydroxide  (Mn(OH)2),  obtained  by  adding 
sodium  hydrate  to  a  manganous  solution,  as  a  nearly  white 
gelatinous  mass,  becomes  rapidly  brown  in  colour  by  absorp- 
tion of  oxygen  from  the  air,  thus  passing  into  one  of  the 
higher  oxides.  It  finds  use  as  a  pigment  and  in  the 
ceramic  industries. 

The  higher  oxides  of  manganese  are  useful  sources  of 
oxygen  gas. 

Manganate  and  Permanganate  of  Potassium  —  Two  com- 
pounds of  manganese  with  potassium  and  oxygen  are  well 
known  as  potassium  permanganate  (KMnO4)  and  manganate 
(K2MnO4),  both  of  which  are  used  as  sanitary  reagents, 
being  valued  on  account  of  their  oxidizing  properties  ;  and 
there  are  corresponding  sodium  compounds,  all  of  which 
are  used  in  tanning  and  bleaching  processes. 

By  fusing  black  oxide  of  manganese  together  with  potas- 
sium hydrate  or  carbonate,  the  green  manganate  is  obtained 
by  dissolving  in  water,  whilst  the  crystalline  red  permanga- 
nate is  now  chiefly  made  by  the  electrolysis  of  the  manganate 
solution  at  a  temperature  of  about  60°,  using  iron  electrodes. 

Another  method  of  manufacturing  potassium  perman- 
ganate consists  in  first  of  all  making  sodium  permanganate 
by  fluxing  manganese  ore  with  caustic  soda  (with  or  without 
the  addition  of  sodium  nitrate  as  an  oxidizer)  dissolving  the 
product  after  grinding,  in  water,  and  treating  the  solution 
with  chlorine  and  sulphuric  acid,  or  alternatively  with 
carbon  dioxide,  to  transform  the  manganate  into  perman- 
ganate of  sodium,  and  subsequently  mixing  the  filtered 
concentrated  permanganate  liquor  with  the  theoretical 
amount  of  potassium  chloride,  and  again  concentrating 
the  mixture  by  heat,  when  the  potassium  permanganate 
crystallizes  out  upon  cooling. 

The  salts  of  manganese  are  flesh  or  pink  coloured. 

Manganese  Chloride  (MnCl2)  is  a  soluble  salt  which  can 
be  obtained  in  crystalline  form  as  MnCl2,4H2O. 


MA  NGA  NESE—MA  NIOC  307 

MANGANESE  (Continued)— 

Manganese  Sulphate  (MnSO4)  is  obtained  in  crystalline 
form  combined  with  water  (MnSO4,5H2O),  and  is  used  in 
ceramics  and  textile  dyeing. 

Manganous  Sulphide  (MnS)  is  a  flesh-coloured,  insoluble 
substance,  obtained  by  adding  an  alkaline  sulphide  solution 
to  one  of  a  manganous  salt. 

Manganous  Carbonate  (MnCO3)  in  precipitated  form  is  a 
slightly  rose-coloured,  insoluble  substance. 

Manganese  Borate  is  a  white  powder,  prepared  by  pre- 
cipitating solutions  of  manganese  salts  with  one  of  borax, 
and  has,  when  dry,  the  composition  MnH4(BO3)2H2O, 
losing  its  water  of  crystallization  upon  heating  to  100°  C., 
and  at  higher  temperatures  becoming  Mn(BO3)2.  It  is 
used  as  a  drier  for  varnishes  and  in  the  oxidation  of  linseed 
oil,  and  is  superior  to  lead  driers  but  inferior  to  manganese 
dioxide,  having,  however,  the  advantage  of  not  darkening 
the  oil  so  much. 

Manganese  Resinate  (Mn(C20H29O2)2) — A  dark,  nearly 
black  substance  prepared  by  boiling  manganese  hydroxide 
with  rosin  oil  and  water.  It  is  soluble  in  hot  linseed  oil, 
and  is  used  in  common  with  manganese  borate  and  man- 
ganese oleate  as  a  varnish  and  oil  drier. 

A  manganese  drier  is  also  prepared  by  heating  together 
common  resin  and  manganese  peroxide  in  certain  pro- 
portions. 

Manganese  Oleate  (Mn(C18H83O2)2)  is  prepared  by  boiling 
manganese  chloride  with  sodium  oleate  and  water,  and  is  a 
dark  brown  substance  soluble  in  oleic  acid. 

Manganese  Acetate  (Mn(C2H3O2)24H2O)— A  pale  red 
crystalline  salt,  soluble  in  water;  used  in  textile  dyeing 
and  manufacturing  bistre. 

MANGANITE — A  crystalline  manganese  ore  (Mn2O3,H2O). 

MANGROVE — A  tannin  material  derived  from  the  mangrove 
(Rhizophora  mangle),  growing  in  Mozambique,  Parapet, 
Pomba  Bay,  and  other  parts  of  East  Africa,  also  West 
Africa  and  Borneo,  containing  from  35  to  40  per  cent, 
tannin. 

MANILLA — Hemp  fibre  used  for  making  certain  qualities  of 
cigarette  and  other  papers. 

MANIOC — The  nutritious,  starchy  matter  of  Jatropha  manihot 
from  which  cassava  and  tapioca  are  made  in  the  West 
Indies. 


308  MA  NNA  -MARGA  RINE 

MANNA — The  dried  juice  or  sap  of  the  manna  ash  (Fraxinus 
ornus)  which  grows  in  Calabria,  Sicily,  and  in  the  East. 
It  contains  from  30  to  60  per  cent,  of  mannitol  (C6H14O6). 

MANNITE  or  MANNITOL  (C6H14O6  or  C6H8(OH)6)— The 
chief  constituent  of  manna.  It  is  a  white,  crystalline  body, 
soluble  in  water  and  to  some  extent  in  alcohol,  and  can  be 
produced  by  the  action  of  sodium  amalgam  on  the  mixture 
of  dextrose  and  laevulose  (C6H12O6)  that  results  from  the 
action  of  dilute  sulphuric  acid  upon  cane  sugar  when  boiled 
together.  It  is  not  very  sweet,  melts  at  about  165°  C., 
and  by  the  action  of  dilute  nitric  acid  is  converted  into 
mannitic  acid  (C6H12O7  or  C6H6O(OH)6).  Chemically,  it  is 
regarded  as  a  polyhydric  alcohol  derived  from  mannose, 
the  last-named  substance  being  stereo-isomeric  with  one  of 
the  glucoses  comprehended  in  the  monosaccharoses.  It 
can  be  made  to  replace  glycerol  in  fats.  (See  Olive  Oil.) 
It  can  be  distilled  without  appreciable  decomposition,  and 
does  not  ferment  except  under  unusual  conditions.  (See 
Carbohydrates  and  Saccharoses.) 

MANURES— See  Fertilizers. 

MARBLE — Crystalline  limestone.     (See  Calcium.) 

MARC — The  refuse  material  resulting  from  pressure  of  seeds 
fruits,  and  herbs,  from  which  extracts  have  been  pre- 
pared. 

MARGARIC  ACID  (C^H^Ojj)— The  substance  described  under 
this  name  as  one  or  the  higher  fatty  acids,  melting  at  60°  C., 
is  now  regarded  as  being,  in  reality,  a  eutectic  mixture  of 
palmitic  and  stearic  acids. 

MARGARINE — A  butter  substitute,  manufactured  on  a  large 
scale,  consisting  of  fatty  acids  or  oils  from  various  sources, 
compounded  with  skim-milk  sterilized  by  heating  to  82°  C., 
and  sometimes  inoculated  with  the  butyric  ferment  (lactic 
acid  bacilli)  in  order  to  give  the  blended  mixture  a  butter- 
like  odour. 

Cotton-seed,  palm,  cocoa-nut,  and  arachis  oils  are  largely 
used,  and  in  some  cases  animal  fats,  such  as  "  premier 
jus  "  and  lard,  are  admixed  with  the  vegetable  oils,  so  pro- 
portioned as  to  give  a  melting-point  of  about  20°  C. 

Stearine,  being  more  solid  at  the  ordinary  atmospheric 
temperature,  is  used  when  necessary  to  counteract  the 
more  liquid  oils  and  to  adjust  the  desired  consistency. 

The  fats  produced  by  the   hydrogenation   process  (see 


MARGA  RINE—MA  STIC  3<*) 

MARGARINE  (Continued)— 

Hydrogen,  p.  252)  from  whale,  cotton-seed,  and  other  oils 
are  now  extensively  used  to  replace  the  animal  fats  pre- 
viously employed  in  making  the  best  qualities. 

The  process  of  making  is  somewhat  as  follows :  The 
milk,  after  cooling  to  10°  C.,  is  churned  with  the  melted 
mixture  of  fats  and  oils  at  a  temperature  of  25°  to  35°  C. 
until  thoroughly  emulsified,  then  cooled,  and  after  maturing, 
to  allow  the  butyric  ferment  to  do  its  work,  kneaded  to 
expel  the  excess  of  water  over  16  per  cent,  which  is  the 
legal  limit.  It  is  essential  that  the  oils  ^  should  be  run 
slowly  into  the  milk  in  the  churn,  to  produce  a  fine-grained 
permanent  emulsion  of  the  oil-in-water  type,  as  if  the 
reverse  method  be  used,  an  emulsion  of  the  water-in-oil 
type  results,  and  is  not  so  satisfactory.  (See  Emulsions.) 

The  English  production  of  margarine  in  1915  was  esti- 
mated at  240,000  tons. 

MARJORAM  OIL— The  essential  oil  of  the  aromatic  herb 
Origanum  majorana,  containing  terpineol  and  terpenes.  It  is 
soluble  in  alcohol  and  ether,  and  is  used  in  perfumery  and 
medicine.  Its  sp.  gr.  is  0-89  to  0-91. 

MARL — Earth  consisting  of  clay,  chalk,  and  sand. 

MARMATITE — A  ferruginous  variety  of  blende  (in  which  the 
zinc  is  partly  replaced  by  iron  and  manganese)  occurring 
in  the  Broken  Hill  concentrates. 

"MARMITE" —  A  food  preparation  resembling  extract  of 
meat,  prepared  from  yeast.  (See  Proteins.) 

MARSH  GAS — A  mixture  of  methane  (CH4)  with  carbon 
dioxide  and  nitrogen,  formed  in  nature  by  the  decomposition 
of  organic  bodies  under  water.  (See  Methane.) 

MARSH'S  TEST— See  Arsenic. 

MASS — Under  constant  conditions,  the  rate  of  chemical  change 
is  proportional  to  the  mass  of  the  reacting  substances. 

MASSICOT— A  mineral  form  of  lead  monoxide  (PbO)  found 
in  some  of  the  United  States  of  America. 

MASTIC — The  name  of  a  resinous  exudation  obtained  from 
incisions  made  in  the  bark  of  the  Pistacia  lentiscus  growing 
in  Chios  and  other  islands  of  the  Grecian  Archipelago.  It 
occurs  in  the  form  of  small,  yellow,  translucent  tears ;  is 
soluble  in  alcohol,  acetone,  and  turpentine,  and  is  used 
among  other  applications  for  lacquer  and  varnish 
and  as  a  chewing-gum. 


310  MASTIC— MATTER 

MASTIC  (Continued)— 

The  same  name  mastic  or  gum  mastic  is  employed  to 
designate  some  forms  of  native  bitumen. 

MATCHES— See  Phosphorus. 
MATLOCKITE— An  ore  of  lead  (PbCl2,PbO). 

MATTE  (Mat) — Impure  copper  sulphide  in  a  fused  state  pre- 
pared in  course  of  the  production  of  metallic  copper  from 
its  ore.  By  further  roasting,  it  is  converted  into  so-called 
"  fine  metal "  or  a  purer  sulphide,  and  by  a  repetition  of  the 
roasting  in  a  current  of  air,  the  metallic  copper  is  obtained 
by  burning  off  the  sulphur  constituent. 

MATTER — The  substance  of  the  chemical  elements  and  their 
compounds  of  which  the  universe  is  composed,  capable  of 
assuming  three  distinct  physical  states — namely,  the  fluid, 
solid,  and  gaseous.  Water  in  its  ordinary  form,  that  of  ice, 
and  that  of  steam,  is  exemplary.  Again,  liquid  mercury 
(quicksilver)  can  be  frozen  to  a  solid  and  vapourized  by 
heat.  The  various  kinds  of  matter  are  characterized  by 
their  properties.  Matter  is  indestructible;  only  its  forms 
can  change. 

In  a  sense — and  that  a  very  definite  one — all  matter  may 
be  said  to  be  alive,  the  liability  to  chemical  change  being 
the  qualification  for  that  description.  Given  the  necessary 
environment,  every  known  substance  and  compound  is 
susceptible  of  change — thus,  for  example,  phosphorus, 
which  is  comparatively  inert  when  kept  under  water, 
becomes  very  much  alive  when  exposed  to  the  air,  and 
even  more  so  when  introduced  into  gaseous  oxygen. 

This  liability  to  change  is  shared  by  the  substances 
of  which  living  tissues  are  formed,  and  even  the  so-called 
death  of  living  creatures  does  not  constitute  death  even  in 
a  material  sense.  It  is  true  that  the  microcosm — the  entity 
— is  changed,  but  the  component  parts  are  each  and  all 
alive  individually,  and  are  subject  to  further  changes  ac- 
cording to  their  environment. 

In  some  speculations,  all  the  forms  of  matter  are  ascribed 
to  simple  differences  in  the  arrangements  and  movements 
of  the  ultimate  particles  of  positive  and  negative  electricity, 
which  in  this  view  are  the  two  primordial  elements. 

The  basic  nature  of  primordial  matter  is  as  yet  largely 

problematical.     Whatever  matter  may  be  essentially,  it  is 

irrevocably  bound  up  with  force — the  one  with  the  other — 

*  and  probably  both  are  comprehended  and  included  in  what 

we  know  as  "  chemical  affinity." 


MATTER—MENTHOL  311 

MATTER  (Continued)— 

The  mean  density  of  the  earth  has  been  experimentally 
determined  as  5*6747  times  that  of  water.  (See  Elements, 
Electrons,  and  Radio-activity.) 

MAUVE — The  first  aniline  dye  prepared  in  this  country,  being 
one  of  the  so-called  "  safranines  "  group.  It  is  a  crystalline 
substance  of  green  lustre  which  dyes  mauve,  but  the  colour 
fades  in  sunlight.  It  is  used  for  colouring  postage  stamps, 
amongst  other  applications. 

MEASURES — See  Burettes,  Pipettes,  and  Weights  and 
Measures. 

MEERSCHAUM  (SEPIOLITE  or  SEAFOAM)— A  very  light 
deposit  having  a  sp.  gr.  of  o(8  to  1*0  found  in  certain 
alluvial  deposits  in  Asia  Minor,  Greece,  and  elsewhere, 
consisting  of  a  hydrated  silicate  of  magnesium.  It  is,  as 
a  rule,  slightly  yellow  in  colour,  and  is  used  for  making 
pipe-bowls  and  other  articles.  Talc  and  serpentine  are 
other  varieties  of  magnesium  silicate. 

MELISSIC  ACID  (C30H60O2)— One  of  the  higher  members  of 
the  fatty  acids,  with  a  melting-point  of  90°  C. 

MELITRIOSE  (Mellitose)— See  Raffinose. 

MELLITIC  ACID  (C12H6O12)— Occurs  in  peat  as  so-called 
honeystone  (mellite),  or  aluminium  mellitate  (C12Al2Oi2, 
i8H2O).  When  pure,  it  is  a  white,  crystalline  body,  soluble 
in  water  and  alcohol,  of  polybasic  character,  and  can  be 
obtained  from  lignite  or  graphite  by  oxidation  with 
potassium  permanganate. 

MENHADEN  OIL— See  Fish  Oils. 

MENISCUS — The  curved  surface  of  a  liquid  confined  in  a  tube 
due  to  capillarity,  as  witnessed  in  a  solution  contained  in 
a  burette  or  the  column  of  mercury  in  a  barometer. 

MENSTRUUM — A  solvent  liquid  used  for  extracting  the 
soluble  parts  of  a  substance. 

MENTHENE  (C10H18) — A  terpene  obtained  from  menthol  by 
elimination  of  water. 

MENTHOL  (Mint  Camphor)  (C10H20O)— A  colourless,  crystal- 
line, camphoraceous  substance  which  is  deposited  from 
peppermint  oil  when  kept  for  a  long  time,  or  cooled  to  a 
low  temperature,  and  large  quantities  of  which  are  imported 
from  Japan.  It  melts  at  44*5°  C.,  is  soluble  in  alcohol  and 
ether,  and  is  nearly  related  to  menthene  (C10H18),  which 
can  be  obtained  from  it  by  elimination  of  water  (as,  for 


312  MENTHOL—  MERCURY 

MENTHOL  (Continued)— 

example,  by  the  action   of  phosphorus  pentoxide).     It  is 
used  medicinally,  and  in  perfumery  and  confectionery. 

MENTHONE  (C10H18O)  is  a  ketone  related  .to  menthol 
(C10H20O)  and  occurs  with  that  substance  as  a  constituent 
of  oil  of  peppermint,  and  both  it  and  menthol  can  be 
produced  chemically  from  the  oil  of  Eucalyptus  dives.  (See 
Thymol.) 

MERCAPTANS  (Thio-Alcohols)  —  A  group  of  organic,  liquid, 
inflammable  compounds  containing  sulphur,  analogous  to 
the  monohydric  alcohols.  They  have  a  very  sharp,  un- 
pleasant odour,  are  insoluble  in  water  but  soluble  in  alcohol. 
Their  relationship  to  alcohol  is  shown  by  the  two  illustrative 
formulae  : 


thyl  alcohol.    C»**f  JS—  ethyl  thio-alcohol 


They  may  be  prepared  by  several  methods  —  as,  for  example, 
by  heating  alcohol  with  phosphorus  pentasulphide,  the 
oxygen  being  thus  replaced  by  sulphur. 

MEBCERIZATION  —  A  treatment  by  which  a  silk-like  lustre  is 
given  to  cotton  clothes  or  yarns  as  effected  by  the  action 
of  a  20  to  25  per  cent,  solution  of  caustic  soda  upon  them 
while  kept  in  a  stretched  condition  so  as  to  prevent  shrink- 
ing of  the  fibres.  The  soda  is  subsequently  washed  out 
with  water.  The  cotton  fibre  which  is  naturally  a  flattened 
hollow  riband  or  tube  swells  up  under  this  treatment  by 
thickening  into  a  cylinder  with  practically  no  hollow  space, 
stronger  than  the  unprepared  cotton  and  more  easily  dyed. 
(See  Silk,  Artificial.) 

MERCURY  (Hydrargyrum,  Hg)  and  its  Compounds  —  Mercury 
(quicksilver)  —  atomic  weight,  200-6;  sp.  gr.  at  o°  C.,  13*596; 
melting-point,  —  z&'Sj0  C.  —  occurs  in  nature  to  some  extent 
in  the  free  or  globulous  state  admixed  with  its  ores  (par- 
ticularly the  sulphide)  of  which  cinnabar  (HgS)  is  the  best 
known.  It  is  found  in  Austria,  Italy,  Mexico,  Spain, 
California,  China,  Japan,  etc.  The  world's  production  in 
1913  was  4,200  tons. 

Mercury  is  made  from  the  natural  sulphide  by  roasting 
the  ore,  whereby  the  sulphur  is  burnt  off  as  sulphur 
dioxide  (SO2),  or  by  heating  the  ore  mixed  with  lime  in 
closed  retorts.  In  this  last-named  process,  the  lime  com- 
bines with  the  sulphur,  whilst  the  mercury  is  liberated  and 
distils  over  as  vapour  which  condenses  upon  cooling  into 
the  well-known  liquid  form, 


MERCURY  AND  ITS  COMPOUNDS  31.3 

MEECUEY  (Continued) — 

Mercury  is  one  of  the  chemical  entities  supposed  to 
consist  of  isotopes,  and  their  partial  separation  can  be 
effected,  as  recently  claimed,  by  evaporating  the  metal  at 
low  pressure  and  condensing  the  evaporated  atoms  on  a 
cooled  surface,  the  density  of  the  condensed  mercury  being, 
it  is  stated,  slightly  lower  than  that  of  the  residual  metal. 

Apart  from  its  uses  in  the  construction  of  thermometers 
and  barometers,  it  is  largely  used  in  making  mirrors, 
amalgams,  extraction  of  gold  from  its  ores,  in  the  manu- 
facture of  vermilion,  and  in  various  electrical  applications. 

It  is  a  bright,  silver-coloured,  liquid  metal  which  solidifies 
at  about  -  38-85°  C.  in  a  crystalline  condition. 

It  readily  combines  with  many  other  metals,  forming 
alloys  or  combinations  which  are  called  amalgams.  Tin 
amalgams  are  used  in  making  mirrors,  while  amalgams  of 
tin  and  copper  are  used  in  dentistry  as  fillings  or  stoppings 
for  teeth.  (See  Amalgams. ) 

Oxides  of  Mercury — When  submitted  to  long  heating  in 
the  air  above  300°  C.,  the  metal  is  slowly  converted  into 
the  red  mercuric  oxide  (HgO),  whereas  when  this  oxide  is 
heated  to  redness  it  is  again  decomposed  into  its  constituent 
elements.  The  red  oxide  is  used  as  a  pigment  and  for 
making  anti-fouling  marine  paints. 

Mercury  forms  several  other  combinations  with  oxygen. 

The  salts  of  mercury  corresponding  to  the  lower  or 
mercurous  oxide  (Hg2O)  are  styled  "  mercurous,"  and  those 
corresponding  to  the  higher  (mercuric)  oxide  (HgO)  are 
classified  as  "  mercuric  "  compounds. 

The  lower  oxide  is  precipitated  in  a  dark  brown  form  in 
hydrated  state  when  an  alkali  is  added  to  a  mercurous  salt 
in  solution. 

Mercurous  Chloride  (Hg2Cl2)  (calomel)  is  a  white,  crystal- 
line body,  insoluble  in  water,  used  in  medicine. 

Mercuric  Chloride  (HgCl2),  or  corrosive  sublimate,  as  it 
is  also  known,  is  a  white,  crystalline  substance,  soluble  in 
water,  and  is  possessed  of  poisonous  and  very  powerful 
antiseptic  and  germicidal  properties,  for  which  reason  it  is 
used  by  taxidermists  in  preparing  the  skins  of  animals,  also 
by  surgeons  (in  very  dilute  solution)  as  an  antiseptic  wash. 

Mercuric  Sulphate  (HgSOJ  is  a  white,  crystalline  sub- 
stance, insoluble  in  water,  used  in  the  preparation  of  the 
two  chlorides  and  in  the  extraction  of  gold  and  silver  from 
roasted  pyrites. 

Mercuric  Iodide  (HgI2)  is  insoluble  in  water  and  is  di- 


314  MERCURY—METALS 

MERCURY  (Continued)— 

msorphous  ;  when  heated  to  150°  C.  the  scarlet  crystals  are 
changed  into  another  and  yellow  crystalline  form,  but  which 
upon  being  lightly  touched  is  at  once  retransformed  into  the 
original  state. 

Mercuric  Nitrate  (Hg(NO3)22H2O)  is  a  crystalline,  soluble 
salt,  of  deliquescent  character,  used  in  medicine  and  felt 
manufacture. 

Mercuric  Sulphide  (HgS),  as  obtained  by  the  precipitation 
of  a  mercuric  salt  with  hydrogen  sulphide,  is  black  and  in- 
soluble ;  but  when  washed,  dried,  and  sublimated,  it  becomes 
red,  forming  the  so-called  "  vermilion,"  in  which  form  it  is 
manufactured  for  use  as  a  pigment  and  for  colouring  sealing- 
wax  (red). 

Mercuric  Cyanide  (Hg(CN)2)  is  colourless,  crystalline, 
and  soluble  in  water.  It  is  used  for  making  cyanogen  gas 
and  in  photography. 

Mercury  Fulminate — See  Fulminating  Mercury. 
All  the  mercury  compounds  are  poisonous. 

MET  A -COMPOUNDS — Substitution    products    derived    from 
benzene  in  which  the  substitutory  radicals  or  groups  are 
constitutionally  placed  in  certain  definite  positions  in  the 
nucleus — meta-cresol,  for  instance. 
META-CRESOL— See  Cresol. 

METALS — The  metallic  elements  as  a  class  are  capable  of 
taking  a  high  polish,  but  some,  of  course,  more  than  others. 
Gold,  copper,  and  platinum,  for  example,  may  be  polished 
and  burnished  to  a  very  high  degree — much  more  than  iron, 
lead,  and  arsenic. 

Again,  some  are  much  more  ductile  than  others,  and  can 
therefore  be  easily  drawn  out  into  wire.  For  example, 
copper  in  this  form  is  largely  used  for  telegraphic  purposes. 

Others  are  of  a  malleable  character — that  is  to  say,  can  be 
easily  beaten  into  any  desired  shape  with  a  hammer  or 
mallet — lead,  for  example.  Gold  and  several  other  metals 
can  be  hammered  into  extremely  thin  sheets — gold  leaf,  for 
example.  (See  p.  234.) 

Most  metals  are  good  conductors  of  heat,  sound,  and 
electricity.  At  a  temperature  approaching  absolute  zero, 
pure  metals  lose  practically  all  electrical  resistance  and 
become  nearly  perfect  conductors. 

There  are  great  differences  between  the  hardness,  brittle- 
ness,  weight,  tensile  strength,  and  other  properties  of  the 
various  metals. 


METALS— METALLIC  ORGANIC  COMPOUNDS       315 

METALS  (Continued)— 

The  following  table  comparing  the  production  within  the 
Empire  with  the  estimated  normal  consumption  apart  from 
special  war  demands  is  taken  from  a  recent  British  Official 
Report : 

Production.  Consumption. 

Tons.  Tons. 

Iron          ...             ...     4,600,000  7,000,000 

Tin           ...             ...            5,100  21,000 

Lead         ...             ...          17,000  179,000 

Zinc          ...             ...            4,800  185,000 

Copper     ...             ...               140  130,000 

Manganese  (ore)     ...            4,500  400,000 

Wolfram...             ...               260  4,000 

The  individual  metals  and  their  characters  are  described 
under  their  respective  names.  (See  also  Alloys.) 

TABLE  OF  MELTING  OR  FUSING  POINTS  OF  SOME  IMPORTANT 
METALS  AND  THEIR  SPECIFIC  GRAVITIES. 

Aluminium  ...  ...  6587°  C.  2-58 

Antimony  ...  ...  ...  630°  C.  6-7 

Bismuth     ...  ...  ...  271°  C.  9-823 

Cadmium  ...  ...  ...  320-9°  C.  8-642 

Chromium...  ...  ...  1,615°  C.  6-92 

Copper       ...  ...  ...  i,o83°C.  8-95 

Wrought  Iron  ...  ...  1,600°  C.  7*80 

Lead          ...  ...  ...  327-4°  C.  11-3 

Manganese  ...  ...  1,230°  C.  8-0 

Silver          ...  ...  ...  960-5°  C.  10-5 

Tin             ...  ...  ...  231-9°  C.  7-2 

Zinc            ...  ...  ...  419*4°  C.  6*9 

Platinum   ...  *  ...  ...  1,775°  C.  21'5 

Steel          ...  about  1,350°  to  1,375°  C-     about  7-60  to  7-80 

METALLIC  CARBONYLS— Compounds  of  metals  with  carbon 
monoxide,  the  nickel  compound  being  NifCO)^.  (See 
Nickel.)  An  iron  compound — a  pale  yellow,  viscid  liquid 
(Fe(CO)g) — is  also  known. 

METALLIC  ORGANIC  COMPOUNDS— These  include  mercury 
phenyl  (Hg(C6H6)2),  which  is  obtained  by  the  action 
of  sodium  amalgam  on  bromo-benzene ;  tin,  lead,  and 
magnesium  form  corresponding  compounds.  Other  organo- 
metallic  compounds  are  described  under  the  respective 
metals,  arsenic,  antimony,  boron,  silicon,  platinum,  etc. 


316      METALLIC  NITROXYLS— METHYL  CHLORIDE 

METALLIC  NITROXYLS — Combinations  of  metals  with  nitric 
peroxide,  such  as  copper  nitroxyl  (Cu2NO2),  formed  by  the 
action  of  nitric  peroxide  on  metallic  (reduced)  copper. 

METALLOID — A  term  sometimes  given  to  those  elements  such 
as  arsenic  and  selenium  which  are  not  decidedly  metallic, 
but  appear  to  occupy  a  position  on  the  borderland  between 
the  absolutely  metallic  and  non-metallic  elements. 

METALLURGY — The  art  of  extracting  and  working  in  metals. 

METAMERIC — Substances  which  have  the  same  molecular 
weights  and  identical  percentage  composition,  but  are  of 
different  types  and  structure  and  furnish  different  products 
by  chemical  changes,  such  as  acetone  (CO(CH3)2)  and 
allyl  alcohol  (C8HB(HO)). 

METAMORPHISM  —  The  changes  in  minerals  (rocks)  of 
chemical  and  physical  characters. 

METEORITES — Mineral  substances  of  meteoric  origin  which 
have  fallen  on  the  earth's  surface — some  of  iron  or  iron 
alloyed  with  nickel ;  many  others  are  composed  of  silicates 
or  of  the  various  elements  entering  into  the  composition  of 
terrestrial  minerals.  Most  of  them  are  fused  on  their  sur- 
faces, doubtless  brought  about  by  their  rapid  passage 
through  the  atmosphere. 

METHANE — See  Hydrocarbons  and  Marsh  Gas. 

METHYL  ACETATE  (CH3CO2.CH8)— A  colourless,  fragrant, 
volatile  liquid,  of  sp.  gr.  0-9244  and  boiling-point  54°  C. ; 
soluble  in  water,  alcohol,  and  ether;  made  by  heating 
methyl  alcohol  and  acetic  acid  in  presence  of  sulphuric  acid 
and  distilling.  It  is  used  as  a  solvent,  in  perfumery,  and 
making  extracts. 

METHYL  ALCOHOL— See  Alcohols. 

METHYL  BENZOATE  (Essence  Niobe)  (C6H5.CO2.CH3)— A 
colourless  solution  ofsp.gr.  1-09  and  boiling-point  i98-6°C.; 
soluble  in  water  and  alcohol,  used  in  perfumery,  and  pre- 
pared by  heating  benzoic  acid  and  methyl  alcohol  in  the 
presence  of  sulphuric  acid. 

METHYL  BLUE — See  Aniline  and  Dimethylaniline. 

METHYL  CHLORIDE  (Chloromethane)  (CH3C1)  is  a  colourless 
gas  of  ethereal  odour,  used  in  medicine  and  for  refrigera- 
tion, prepared  by  the  action  of  hydrochloric  acid  on  methyl 
alcohol  in  the  presence  of  sulphuric  acid.  It  boils  at 
27-7°  C.  and  is  soluble  in  water  and  alcohol. 


METHYL  CINNAMATE—"METOL"  317 

METHYL  CINNAMATE  (C6H6CH.CHC92.CH3)  (prepared 
from  cinnamic  acid  and  methyl  alcohol  in  the  presence  of 
sulphuric  acid,  followed  by  distillation)  is  a  colourless, 
crystalline  substance,  of  melting-point  36°  C.,  boiling- 
point  259*6°  C. ;  soluble  in  alcohol  and  ether,  and  used 
for  flavouring  and  in  making  perfumery. 

METHYL  ETHEE— See  Ethers. 

METHYL  IODIDE  (CH3I) — A  liquid  halogen  derivate,  soluble 
in  alcohol. 

METHYL  SALICYLATE  (C6H4(OH)COO,CH3)— The  prin- 
cipal constituent  of  oil  of  wintergreen.  A  colourless  liquid 
of  sp.  gr.  1-185  and  boiling-point  222-2°  C.,  soluble  in 
alcohol  and  ether.  Chemically,  it  is  the  methyl  ester  of 
salicylic  acid. 

The  artificial  oil  of  wintergreen  is  prepared  by  heating  a 
mixture  of  methyl  alcohol  and  salicylic  acid  in  presence  of 
sulphuric  acid.  It  is  used  in  medicine,  and  for  flavouring 
purposes.  (See  Oil  of  Wintergreen.) 

METHYL  SULPHONAL— An  organic  body  of  complicated  con- 
stitution known  under  the  trade  name  of  "Trional,"  and 
used  as  an  hypnotic. 

METHYL  VIOLET — A  synthetic  dye.     (See  Aniline.) 
METHYLAMINE — See  Amines. 

METHYLATED  SPIRIT — A  mixture  of  alcohol  with  10  per 
cent,  of  common  wood-spirit,  tainted  (denatured)  with  other 
substances,  such  as  paraffin  oil,  to  render  it  unfit  for  con- 
sumption, but  available  for  chemical  and  manufacturing 
purposes,  as  an  alcoholic  solvent  and  fuel. 

METHYLENE  (CH2)  —  The  hypothetical  first  member  of  the 
olefine  series  of  hydrocarbons,  but  which,  so  far  as  is  known, 
does  not  exist.  The  dichloride  (CH2C12)  is  a  volatile  liquid 
used  as  a  local  anaesthetic. 

METHYLENE  BLUE,  or  Tetramethyl-Thionate  Hydrochloride 
(C16H18N3SC1),  is  used  as  a  bacteriological  stain;  also  in 
medicine  and  in  dyeing  cotton  yarns. 

METHYLENE  CHLORIDE,  or  Dichloromethane  (CH2C12),  is  a 
colourless,  volatile  liquid  of  sp.  gr.  1-2615  and  boiling-point 
42°  C.,  soluble  in  alcohol  and  ether,  used  as  a  local  anaes- 
thetic, and  prepared  by  the  chlorination  of  methyl  chloride, 
followed  by  distillation. 

"METOL"—  A  cresol  derivative  used  as  a  photographic 
developer. 


3i8  METRE—MILK  OF  SULPHUR 

METRE— See  Weights  and  Measures. 
METRIC  SYSTEM— See  Weights  and  Measures. 

MICA — The  somewhat  general  name  of  a  number  of  minerals, 
including  Muscovite,  having  a  more  or  less  laminated  or  so- 
called  micaceous  character.  For  the  most  part,  they  are 
hydrous  silicates  of  magnesium  and  potassium,  but  they  are 
of  varying  and  complicated  composition.  Considerable  sup- 
plies come  from  India  and  the  Argentine,  where  there  is  a 
growing  industry  in  the  material. 

The  uses  of  mica  in  the  arts  are  similar  to  those  of  talc. 

MICROBES,  or  MICRO-ORGANISMS,  are  extremely  minute 
living  organisms  by  whose  agency  the  processes  of  decay, 
putrefaction,  many  fermentations,  and  other  chemical 
changes  are  brought  about.  Some  of  them  play  an  important 
part  in  connection  with  infectious  diseases  and  they  are 
roughly  divided  into  two  classes — viz. ,  aerobes,  which  require 
oxygen  for  their  sustenance,  and  anaerobes,  which  cannot 
live  in  oxygen,  and  are  killed  by  exposure  thereto.  The 
function  of  anaerobes  would  appear  to  be  largely  in  the 
nature  of  hydrolysis  (see  Hydrolysis),  and  that  of  aerobes 
one  of  oxidation.  (See  also  Bacteria,  Nitrification,  and 
Sewage.) 

MICROCOSMIC  SALT — A  compound  phosphate  of  hydrogen 
sodium  and  ammonium  (Na(NH4)HPO4,4H2O)  obtained  by 
mixing  solutions  of  ordinary  sodium  phosphate  and  ammo- 
nium chloride. 

MICROSCOPE— An  instrument  so  constructed  as  to  magnify 
the  objects  looked  at  through  it.  When  it  has  only  one 
lens  it  is  termed  a  simple  microscope,  but  when  fitted  with 
two  or  more  it  is  known  as  a  compound  microscope. 

MILE — The  sole  natural  food  of  all  the  mammalia  for  some 
time  after  birth.  It  contains  water,  fat,  proteid  substances, 
milk-sugar,  and  certain  salts,  the  relative  proportions  vary- 
ing with  the  species.  Cow's  milk  has  a  sp.  gr.  of  about  i  '03, 
contains  about  14  per  cent,  of  solids,  of  which  about  4  per 
cent,  is  fat,  and  gives  about  0*8  per  cent,  of  ash.  In  souring, 
the  milk-sugar  is  converted  into  lactic  acid.  The  so-called 
"  condensed  milk  "  is  made  by  evaporating  off  a  quantity  of 
its  water — to  about  one  quarter  of  its  original  bulk — sugar 
being  generally  added  at  the  same  time.  It  keeps  well, 
but  as  it  is  generally  made  from  skimmed  milk  it  is  not  so 
nourishing  as  fresh  milk. 

MILK  OF  SULPHUR— See  Sulphur. 


MILK-SUGAR— MIRBANE  (OIL  OF) 


319 


MILK-SUGAR— See  Lactose. 

MILLON'S  TEST,  for  albuminoids  in  suspected  tissues,  consists 
in  moistening  with  a  solution  of  2  parts  mercury  dissolved 
in  4  of  nitric  acid  of  sp.  gr.  1-40,  and  gently  warming, 
when  an  intense  red  colour  is  produced  if  albuminoid 
matter  be  present ;  this  colour  is  not  destroyed  by  boiling 
with  water  or  exposure  to  the  air. 

"MILTON" — A  proprietary  disinfectant  liquid  containing 
sodium  hypochlorite  as  its  active  agent. 

MIMOSA  BARK — The  produce  of  the  Acacia  mimosa,  containing 
an  astringent  principle  used  in  tanning  and  resembling 
cutch  in  character  and  composition.  (See  Cutch.) 

MINERALS — Rocks  and  other  inorganic  materials  found 
naturally. 

The  output  of  minerals  from  all  sources  in  the  United 
Kingdom  in  1919,  as  reported  by  the  Chief  Inspector  of 
Mines,  was  as  follows  : 


Mineral. 

Total  Output. 

Mineral. 

Total  Output. 

Tons. 

Tons. 

Alum  shale     

4,848 

Iron  ore 

12,254,195 

Arsenic 

2,527 

Iron  pyrites    

7,336 

Arsenical  pyrites 

75 

Lead  ore 

13,868 

Barium  compounds  ... 

60,087 

Limestone  (other  than 

9,537,495 

Bauxite 

9,221 

chalk) 

Bog  ore 

3,045 

Manganese  ore 

12,078 

Chalk  

2,629,406 

Cubic  Feet. 

Cheet,  flint,  etc. 

50,082 

Natural  gas    

90,000 

Chromite  of  iron       .  . 

3C5° 

Tons. 

Clays   and    shale  (in- 

7,765,965 

Ochre,  umber,  etc.  ... 

io,547 

cluding  china  clay, 

Oil  shale         

2,763,875 

china     stone,     and 

Rock  salt        

90,938 

mica  clay) 

Salt  from  brine 

1,817,142 

Coal     ...         

229,779,517 

Sandstone       

1,699,853 

Copper  ore  and   pre- 

372 

Slate    

164,098 

cipitate 

Soapstone 

688 

Fluorspar 

36,860 

Strontium  sulphate  ... 

1,872 

Gravel  and  sand 

2,048,427 

Tin  ore  (dressed) 

5,J56 

Gypsum 

220,003 

Tungsten  ores 

166 

Igneous  rocks 

4,387,703 

Zinc  ore 

6,933 

MINERAL  OILS— See  Petroleum. 
MINIUM  (Bed-Lead)— See  Lead. 

MIRBANE  (OIL  or  ESSENCE  OF) — A  trade  name  for  nitro- 
benzene as  used  in  perfumery.     (See  Nitro-benzene.) 


320  MISCIBILITY—  MOLECULES 

MISCIBILITY—  Capability  of  admixture  to  a  state  of  perfection. 
For  example,  vinegar  can  be  admixed  with  water  in  all 
proportions,  and  oil  of  turpentine  is  miscible  with  spirits  of 
wine.  Miscibility  is  a  property  of  gases  also  :  oxygen  gas 
can  be  mixed  with  hydrogen,  for  example  ;  but  solid  bodies 
are  not  miscible  in  the  same  chemical  sense.  (See  Mixtures 
and  Diffusion.) 

MISPICKEL—  Arsenical  pyrites  (FeS2  +  FeAs,,).   (See  Arsenic.) 

MIXTURE  —  This  term  is  not  identical  in  meaning  with  com- 
pound in  the  chemical  sense.  A  mixture  of  lead  shots  and 
powdered  sulphur  can  be  made,  but  it  is  neither  uniform  nor 
a  compound,  as  the  lead  shots  can  be  picked  out  one  by  one. 
Similarly,  iron-filings  can  be  mixed  with  sand,  but  the  iron- 
filings  can  be  abstracted  from  the  mixture  by  means  of  a 
magnet.  (See  Chemical  Compounds  and  Diffusion.) 

"  MOLASOCABB  "  —  A  decolourant  black  made  by  decomposing 
molasses  with  lime,  burning  the  mixture,  and  subsequently 
washing  the  char  with  chemicals  to  remove  the  lime  salts. 

MOLASSES  (Treacle)  —  Uncrystallizable  drainings  from  cane 
sugar,  used  to  some  extent  for  making  glycerine.  It  is 
used  for  sweetening  purposes  and  in  the  preparation  of  rum 
by  fermentation  and  subsequent  distillation  of  the  fer- 
mented product.  A  low-grade  cane  molasses  is  known  as 
"  blackstrap."  (See  Glycerine  and  Sugar.) 

MOLECULES  AND  MOLEOULAE  WEIGHTS—  The  term  mole- 
cules in  a  chemical  sense,  means  the  smallest  quantities  of 
substances  capable  of  existing  in  the  free  (uncombined)  state, 
as  contrasted  with  atoms,  which  are  regarded  as  constituents 
of  molecules  and  the  smallest  parts  of  matter  which  can  par- 
ticipate in  any  chemical  change.  For  instance,  a  molecule 
of  sodium  chloride  (NaCl)  (common  salt)  is  a  combination 
of  an  atom  of  the  metal  sodium  (Na)  with  one  atom  of  the 
gas  chlorine  (Cl)  — 

Na  +  Cl=NaCl 

and  as  the  atomic  weight  of  sodium  is  23  and  that  of 
chlorine  35*5,  it  follows  that  the  molecular  weight  of  the 
compound  is  58*5.  Again,  in  the  production  of  water 
(H2O),  2  atoms  of  hydrogen  (H)  combine  with  i  atom  of 
oxygen  (O)  to  form  a  molecule  of  water  (H2O)  — 

H0 


and  when  water  is  decomposed  by  electrolysis,  its  mole- 
cule yields  2  volumes  of  hydrogen  gas  and  i  volume  of 
oxygen  gas  at  the  same  temperature  and  pressure. 


MOLECULES  AND  MOLECULAR  WEIGHTS 


321 


MOLECULES  AND  MOLECULAR  WEIGHTS  (Continued)— 

It  is  generally  assumed  (although  it  cannot  be  re- 
garded as  absolutely  proven)  that  equal  volumes  of  gases, 
at  the  same  temperature  and  pressure,  contain  the  same 
number  of  molecules,  this  assumption,  which  harmonizes 
with  so  many  known  chemical  facts,  being  known  as 
Avogadro's  law.  If,  then,  equal  given  volumes  of  hydrogen 
and  oxygen  contain  severally  i  molecule  it  follows  that  as 
oxygen  is  known  to  be  16  times  heavier  than  hydrogen, 
which  has  an  atomic  weight  of  i,  and  as  the  molecule  of 
hydrogen  consists  of  2  atoms,  the  molecular  weight  of 
oxygen  must  be  16x2  =  32. 

To  take  another  instance,  hydrochloric  acid  is  a  com- 
bination of  i  atom  hydrogen  gas  with  i  atom  of  chlorine—* 

H  +  C1  =  HC1 

and  the  respective  weights  of  equal  volumes  of  hydrogen 
and  hydrochloric  acid  gases  are  i  and  18-25.  As  the 
weight  of  hydrogen  contained  in  a  molecule  of  hydrochloric 
acid  is  only  one-half  that  of  the  same  element  contained  in 
an  equal  measure  or  volume  of  hydrogen,  and  as  there  is 
only  i  atom  of  hydrogen  in  the  molecule  HC1,  it  necessarily 
follows  that  the  molecule  of  hydrogen  consists  of  2  atoms, 
and  that  the  molecule  of  HC1  must  weigh  36-5,  made  up  of 


Name  of  Element. 

Atomic 
Symbol. 

Atomic 
Weight. 

Molecular 
Weight. 

Molecular 
Symbol. 

Vapour 
Density. 

Hydrogen 
Nitrogen 

H 

N 

I 
H 

2 

28 

H2 

N2 

I 

H 

Oxygen 

O 

16 

32 

02 

16 

Ozone 

O 

16 

48 

03 

24 

Fluorine 

F 

I9 

38 

Fa 

19 

Sodium 

Na 

23 

23 

Na 

"'5 

Phosphorus  ... 

P 

3i 

124 

P4 

62 

Chlorine 

Cl 

35'5 

71 

C12 

35'5 

Potassium     .  .  . 

K 

39 

39 

K 

!9'5 

Zinc  

Zn 

65 

65 

Zn 

32-5 

Arsenic 

As 

75 

300 

As4 

!50 

Bromine        .... 

Br 

80 

1  60 

Br2 

80 

Iodine 

I 

127 

254 

I2 

127 

Mercury 

Hg 

200 

200 

Hg 

100 

21 


322         MOLECULES  AND  MOLECULAR   WEIGHTS 

MOLECULES  AND  MOLECULAR  WEIGHTS  (Continued)— 

i  atom  of  H  weighing  i  and  i  .atom  of  chlorine  weighing 
35*5.     The  molecular  weight  of  chlorine  is  therefore  71. 

The  relative  weights  of  equal  volumes  of  gases  at  the 
same  temperature  and  pressure  are  known  as  their  vapour 
densities,  and  it  will  be  seen  from  the  table  on  p.  321  that 
these  are  one-half  of  the  numbers  representing  their  mole- 
cular weights. 

In  other  words,  the  atomic  weights  of  gases  are,  with  some 
exceptions,  half  the/weights  of  the  volumes  of  them  respect- 
ively, equal  to  the  volume  of  a  molecule  of  hydrogen  gas  at 
the  same  temperature  and  pressure. 

In  those  instances  where  the  vapour  densities  are  identical 
with  the  atomic  weights,  the  molecules  of  the  elements  con- 
sist of  2  atoms,  while  the  molecules  of  sodium,  potassium, 
zinc,  and  mercury  consist  of  i  atom,  and  therefore  their 
atomic  and  molecular  weights  are  identical.  Phosphorus  and 
arsenic  contain  4  atoms  to  each  molecule,  or  in  other  words, 
the  smallest  weight  of  these  substances  which  can  take  part 
in  any  chemical  change  is  a  fourth  of  their  molecular  weight 
or  one-half  of  their  vapour  densities.  (See  Vapour  Densities.) 
The  molecular  weights  of  organic  compounds  are  ascer- 
tained by  determining  the  composition  of  their  several 
combinations,  as  the  mere  analysis  of  them  only  gives  the 
relative  proportions  of  their  ingredients.  For  example,  the 
analysis  of  acetic  acid  shows  that  it  contains  40  per  cent, 
carbon,  6*6  per  cent,  hydrogen,  and  53-4  per  cent,  oxygen, 
and  if  these  percentages  are  divided  by  the  atomic  weights 
of  the  several  constituent  elements  it  will  be  found  that  their 
relative  proportions  are  3-3,  6-6,  and  3-3,  so  that  the  formula 
5  might  be  either  CH2O,  C2H4O2,  or  C3H6O3,etc.  The  analysis, 
however,  of  silver  acetate  shows  that  i  atom  of  hydrogen 
is  replaced  by  i  of  silver,  so  that  the  formula  of  this  salt  is 
C2H3AgO2  (or  Ag,C2H3O2),  and  that  of  acetic  acid  C2H4O2. 
As  regards  volatile  organic  substances,  much  assistance 
is  rendered  by  ascertaining  the  densities  of  their  vapours, 
as  every  molecule  occupies  a  volume  twice  as  large  as  that 
of  an  atom  of  hydrogen. 

There  are  a  number  of  other  contributory  methods  too 
technical  to  be  described  in  this  volume  but  which  may  be 
lightly  referred  to  here.  The  "  cryoscopic  "  method  depends 
upon  the  ascertained  fact  that  in  certain  chemically  allied 
cases,  the  freezing-points  of  solutions  are  depressed  pro- 
portionately to  the  number  of  molecules  of  the  substances 
dissolved  in  equal  volumes  of  the  same  solvents.  The  boiling- 
point  method  depends,  on  the  other  hand,  upon  the  considera- 
tion that  the  boiling-points  are  raised  from  the  same  cause. 


MOLYBDATES—MONAZITE  SAND  323 

MOLYBDATES — Compounds  formed  by  the  action  of  bases 
such  as  the  alkalies  on  molybdenum  trioxide. 

MOLYBDENITE— See  Molybdenum. 

MOLYBDENUM  (Mo) — Atomic  weight,  96 ;  sp.  gr.,  8-56  ;  and 
melting-point,  2,550°  C.  Molybdenum  is  contained  in  the 
mineral  called  molybdenite,  which  is  a  sulphide  (MoS2)  of 
the  metal  (resembling  graphite  in  appearance)  found  in 
Bohemia,  Canada,  and  Sweden.  It  also  occurs  in  molyb- 
denum ochre,  which  is  an  oxide  of  the  metal  (MoO3);  wulfenite, 
a  double  oxide  of  lead  and  molybdenum  (PbMoO4);  and 
molybdite  (Fe2O3,3MoO3,7|H2O),  which  often  accompanies 
molybdenite. 

Upon  roasting  the  native  sulphide  in  a  current  of  air,  the 
sulphur  is  burnt  off  as  sulphur  dioxide  (SO2),  an  oxide  of 
molybdenum  being  left  behind,  and  by  mixing  this  with 
oil  and  charcoal  and  then  strongly  heating  the  mixture,  the 
molybdenum  is  reduced  to  the  metallic  state.  The  metal 
is  also  prepared  by  alumino-thermic  reduction  of  molybdic 
acid  (H2MoO4),  which  can  be  readily  prepared  from  the 
trioxide.  The  metal  is  greyish-white,  brittle,  and  difficult 
to  fuse.  It  is  used  in  place  of  tungsten  to  the  extent  of 
about  i  per  cent,  in  making  high-speed  steel  parts,  such 
as  crankshafts  and  connecting-rods,  and  otherwise  in 
metallurgy. 

When  heated  in  the  air,  it  oxidizes  into  a  yellow  powder, 
having  the  composition  represented  by  MoO3,  and  several 
chlorides  of  molybdenum  are  known. 

MONAZITE  SAND — A  natural  crystalline  phosphate  of  cerium 
and  lanthanum  generally  containing  thorium  compounds 
also,  which  occurs  naturally  in  extensive  deposits  in 
Colorado  and  Carolina,  the  coast  of  Brazil,  and  Travancore 
(a  native  Indian  state  under  British  protection).  The  latter 
deposit  was  discovered  in  1900,  and  in  September,  1914, 
certain  rights  were  obtained  on  behalf  of  a  British  com- 
pany, with  the  result  that  Germany  has  now  lost  its  former 
dominion  over  the  gas-mantle  market.  These  native  deposits 
of  sand  are  freed  from  much  of  the  associated  lighter 
materials  by  sluicing  with  water  and  electro-magnetic 
separation,  so  that  the  purified  product  consists  of  from 
85  to  90  per  cent,  real  monazite,  containing  about  9  per 
cent,  thoria  and  60  per  cent,  of  cerium  oxides.  These  in 
turn  are  subsequently  converted  into  nitrates,  in  which 
form  they  are  marketed  for  use  in  the  incandescent  mantle 
trade. 

Brazilian  monazite  contains  about  6  per  cent,  thorium 


324  MONAZITE  SAND— MOSS  AGATE 

MONAZITE  SAND  (Continued)  — 

oxide,  the  Travancore  and  Ceylon  deposits  about  9  per  cent., 
and  while  some  are  reported  to  contain  as  much  as  18  per 
cent.,  other  varieties  are  devoid  of  this  constituent.  (See 
Gas  Mantles  and  Thorium.) 

MOND  GAS— See  Producer  Gas. 

"  MONEL  "  —A  proprietary  alloy,  consisting  of  approximately 
67  per  cent,  nickel,  28  per  cent,  copper,  and  5  per  cent, 
other  metals  ;  sp.  gr.,  8'82,  and  melting-point,  1,360°  C. 
It  is  of  great  tensile  strength  and  high  resistance  to  many 
corroding  agencies ;  used  for  making  superheated  steam 
fittings  and  parts  of  chemical  plant  used  under  caustic 
alkaline  conditions,  etc. 

MONTAN  or  MONTANA  WAX— When  purified  by  distillation 
with  superheated  steam  is  a  white  bituminous  substance 
soluble  in  carbon  tetrachloride,  benzol,  and  chloroform ; 
extracted  from  the  lignites  of  Saxony  and  Thuringia,  melting 
at  about  from  80°  to  90°  C.,  and  used  in  candle-making  and 
as  a  substitute  for  carnauba  wax,  etc.  (See  Lignite  and 
Waxes.) 

MOONSTONE — Transparent  felspar. 

MORDANTS — Chemical  substances  used  for  fixing  colours  in 
dyeing  and  calico  printing,  the  colouring  matter  being 
thereby  securely  attached  to  the  fibres  of  the  material  in 
the  form  of  coagulated  or  precipitated  compounds  known 
as  "  lakes."  (See  Dyes  and  Lakes.) 

MORPHINE  (C17H19NO3,H2O)— Many  of  its  salts,  including 
the  acetate,  hydrochloride,  nitrate,  and  sulphate,  which  are 
all  soluble  in  water,  are  used  in  medicine.  (See  Opium.) 

MORTAR — A  mixture  of  burnt  lime  slaked  with  water  to  a  thin 
cream,  and  sharp  sand,  the  hardening  and  setting  of  which 
(as  when  used  for  joining  bricks  together)  depends  partly 
upon  drying  and  partly  upon  absorption  of  carbon  dioxide 
from  the  air  by  the  lime,  thus  converting  it  into  calcium 
carbonate  —  CaH2O2  +  CO2  =  CaCO3  +  H2O.  It  contains 
about  73 '4  per  cent,  sand  and  6*5  per  cent.  CaO. 

MORUS  TINCTORIA— See  Fustic. 

MOSAIC  GOLD — An  alloy  of  copper  and  zinc  in  equal  parts, 
also  used  as  the  name  of  a  pigment  made  of  the  golden- 
yellow-coloured  stannic  sulphide  (SnS2). 

MOSS  AGATE — A  variety  of  the  mineral  known  as  chalcedony. 


MOTHER-LIQUOR—MURIATIC  ACID  325 

MOTHER-LIQUOR — The  residual  liquor  after  the  chief  con- 
stituent substance  has  been  removed  from  it  as  far  as 
possible  by  deposition  or  crystallization.  For  example, 
codeine  being  a  more  soluble  substance  than  morphine,  is 
contained  in  the  mother-liquor  after  the  morphine  has 
crystallized  out.  Bromine  is  recovered  from  the  mother- 
liquor  left  from  the  manufacture  of  potassium  chloride. 
(See  Bromine.) 

MOTHER  OF  PEARL— The  brilliant,  silvery,  hard  layer  of 
oyster  and  other  shells. 

MOTOR  GREASE  is  prepared  in  a  number  of  varieties,  ordinary 
soap  being  used  in  many.  One  recipe  is  as  follows : 
Lubricating  oil  of  sp.  gr.  0-900  to  0-910,  80  parts;  stearic 
acid,  15  parts;  and  caustic  soda,  2  parts,  part  of  the  oil 
being  melted  with  the  stearic  acid  and  mixed  with  the  soda 
in  40  per  cent,  solution,  and  the  remainder  of  the  oil  being 
subsequently  incorporated.  Cheaper  grades  are  compounded 
with  lime  soaps. 

MOTOR  SPIRIT— See  Gasoline  and  Petrol. 
MOTTRAMITE— See  Vanadium. 

MOURA  (MOWRA)  OIL — A  yellow,  semi-liquid  fat,  soluble 
in  ether,  benzene,  and  carbon  disulphide,  of  sp.  gr.  0-894 
to  0-898,  extracted  from  the  seeds  of  Bassia  latifolia  (India), 
has  an  odour  like  that  of  cacao  beans,  and  is  used  in  soap- 
making. 

MUCIC  ACID  (C6H10O8)— A  crystalline,  dibasic  acid  prepared 
by  oxidation  of  dulcitol,  gums,  mucilage,  etc.,  sparingly 
soluble  in  cold  water  ;  melting-point,  213°  C. 

MUCILAGE — Gum  prepared  from  seeds  and  roots  which 
contain  large  quantities  of  a  substance  which  swells  up 
with  water  into  a  mucilage.  Such  mucilages  can  be  pre- 
pared from  linseed  and  quince  seed,  but  the  term  now  is 
generally  applied  to  any  kind  of  adhesive  paste.  (See 
Adhesives.) 

MUNDIC — A  Cornish  name  for  iron  pyrites. 
MUNTZ  METAL— See  Copper. 

MUREXIDE  (Ammonium  Purpurate)  (NH4)CgH4N5O0)— A 
purple  colouring  matter  produced  from  uric  acid  by  moisten- 
ing with  nitric  acid  and  gently  warming  with  ammonia. 
Its  production  is  a  test  for  the  presence  of  uric  acid. 

MURIATIC  ACID— An  old  name  for  hydrochloric  acid.  (See 
Chlorine.) 


326  MUSCARINE— MYRRH 

MUSCARINE  (C5H15NO3)— A  very  poisonous  base  contained  in 
toadstool  (Agaricus  muscarius),  which  can  also  be  produced 
from  choline  by  oxidation  with  strong  nitric  acid.  Choline  is 
found  present  in  brain  matter  and  in  the  bile.  (See  Neurine.) 

MUSCOVITE— Common  mica  (Al2O3.SiO2+K2O.SiO2). 

MUSK — An  aromatic,  resinous  substance  used  in  perfumery, 
obtained  from  an  internal  part — the  preputial  follicles — 
of  the  musk  deer  (Moschus  moschiferus)  inhabiting  Tonquin 
and  Thibet.  The  odour  is  due  to  a  ketone  named  muskine 
(C15H280). 

MUSK  (Artificial) — A  nitro-aromatic  compound  (CUH13N3O6). 

MUST — The  juice  of  crushed  grapes  as  expressed  for  wine- 
making. 

MUSTARD — A  condiment  made  from  the  seeds  of  black  and 
white  mustard  (Sinapis  nigra  and  5.  alba)  by  grinding  and 
sifting.  Both  of  them  yield  oil  by  pressure  to  the  extent 
of  36  per  cent,  in  the  case  of  the  white  seed  and  about 
1 8  per  cent,  in  the  case  of  the  black  variety.  This  oil  has 
a  sp.  gr.  of  1-014  to  i -103  and  a  refractive  index  of  I'S^S  to 
I*535*  I*  contains  some  allyl  compounds  and  is  used  in 
medicine.  In  addition  to  this  fixed  oil,  the  seeds  of  the 
black  variety,  after  pressure,  contain  a  glucoside  named 
sinigrine,  which  by  the  action  of  an  enzyme  named  my  rosin 
yields,  upon  moistening  with  water  and  standing,  a  very 
pungent  volatile  oil  containing  sulphur  (allyl  isosulpho- 
cyanate),  together  with  glucose.  The  white  mustard  seeds 
contain  an  alkaloidal  body  named  sinapine. 

MUSTARD  GAS— See  Gassing. 

MYELINES — Complicated  substances  containing  phosphorus, 
which  are  obtained  from  brain  matter ;  they  are  of  crystal- 
line character,  and  soluble  in  hot  alcohol. 

MYRABOLANS — The  dried  fruit  of  the  Chinese  and  Indian 
trees  Myrabolanus  chebula,  which  contain  about  30  per  cent, 
tannin  and  are  used  in  the  tanning  industry. 

MYRCIA  OIL— See  Bay  Oil. 

MYRISTIC  ACID  (C14H28O2)— A  crystalline  fatty  acid  of  the 
normal  series,  present  in  oil  of  iris  and  nutmeg-butter, 
obtained  from  Myristica  moschata.  It  has  a  melting-point 
of  54°  C.  and  is  soluble  in  hot  alcohol. 

MYRISTICIN— See  Nutmeg  Oil. 

MYRRH — A  resinous  gum  which  exudes  from  the  Balsamoden- 
dron  myrrha  (grown  in  Arabia,  Abyssinia,  and  Somaliland), 


MYRRH— NAPHTHALENE  327 

MYRRH  (Continued)— 

associated  with  a  volatile  oil  in  common  with  other  similar 
exudations  from  terebinthaceous  shrubs.  Tincture  of 
myrrh  is  mildly  disinfectant,  and  is  used  as  a  local  stimu- 
lant to  mucous  membranes.  Myrrh  is  also  used  as  a  con- 
stituent of  tooth-powder. 

An  oil  is  distilled  from  the  gum  known  as  myrrh  oil, 
which  has  a  sp.  gr.  of  0*988  to  1*007,  ^s  soluble  in  alcohol 
and  ether,  and  used  in  perfumery. 

MYRTLE  OIL — distilled  from  the  leaves  of  Myvtus  communis — 
is  light  yellow  and  of  agreeable  odour,  containing  cineol, 
dextropinene,  and  dipentene.  It  is  soluble  in  alcohol  and 
ether,  has  a  sp.  gr.  0-89  to  0*92,  and  rotation  +  io°to  +30°, 
and  is  used  in  medicine. 

MYRTLE  or  LAUREL  WAX— A  crystalline  hydrated  glyceride 
obtained  from  the  berries  of  various  species  of  Myrica. 

NAPHTHA — A  more  or  less  general  term  given  to  oily  bodies 
produced  in  the  distillation  of  cannel-coal  and  bitu- 
minous shale,  containing  paraffin  in  solution  of  mixed  hydro- 
carbons. These  are  used  for  illuminating  purposes,  also 
as  solvents.  One  such  liquid  is  found  associated  with 
deposits  of  bitumen  and  asphalt  in  many  places  and  is 
distilled  therefrom. 

Heavy  Naphtha  is  dark-coloured  as  prepared  from  coal 
tar,  has  a  sp.  gr.  of  0-925  to  0-950  and  flash-point  about 
78*3°  C.  It  is  used  as  a  solvent  and  in  paint-making. 

Water- white  Naphtha  has  a  sp.  gr.  of  0-870  to  0-880, 
a  flash-point  not  below  37'8°  C.,  and  is  largely  used  as  a 
solvent.  • 

Solvent  Naphtha  is  a  mixture  of  benzol,  toluol,  xylol,  etc., 
derived  from  coal  tar  distillation.  (See  Coal  and  Petroleum.) 

NAPHTHALENE  (C10H8)— A  solid  hydrocarbon  obtained  from 
coal  tar  and  chiefly  contained  in  the  fraction  that  distils 
between  180°  and  200°  C.,  from  which  it  crystallizes  out  on 
cooling  and  is  subsequently  purified  by  treatment  with  small 
quantities  of  strong  sulphuric  acid,  followed  by  sublimation. 
Pure  naphthalene  crystallizes  in  white  glistening  plates, 
melts  at  80°  C.,  boils  at  218°  C.,  and  is  readily  soluble  in  hot 
alcohol,  benzol,  and  ether.  It  has  a  peculiar  tarry  odour,  and 
is  prepared  commercially  in  the  forms  of  crystals,  flakes, 
balls,  powders,  and  sticks.  It  is  largely  used  in  the 
manufacture  of  artificial  indigo  and  dyes,  also  for  the 


328  NAPHTHALENE— "NARKI"  METAL 

NAPHTHALENE  (Continued)— 

carburation  of  illuminating  coal  gas.  It  possesses  anti- 
septic properties  and  is  carried  in  the  forms  of  balls  and 
sticks  by  the  natives  of  India  and  the  Far  East  as  a  fever 
preventive.  It  is  also  employed  therapeutically,  and  has 
been  advocated  as  a  motor  fuel  in  a  state  of  solution  in 
benzol. 

Mononitro -Naphthalene  (C10H7NO2)  is  used  in  the  pre- 
paration of  explosives  and  dyes. 

Dinitro-Naphthalene  (C10H6(NO2)2)  is  used  in  the  pre- 
paration of  explosives  and  "alizarin  black." 

NAPHTHENES — Constituents  of  Russian  petroleum  to  the 
extent  of  almost  80  per  cent.  They  are  hydrocarbons  of 
the  general  formula  CWH2M,  such  as  cyclopentane  (C5H10) 
and  cyclohexane  (C6H]2)  (isomeric  with  the  olefmes). 
The  American  oil  consists  for  the  most  part  of  paraffin 
hydrocarbons.  (See  Hydrocarbons  and  Petroleum.) 

NAPHTHOL  (Alpha)  (C10H17OH)  is  a  colourless,  crystalline 
substance  which  melts  at  94-2°  C.  and  is  soluble  in  benzol, 
alcohol,,  and  ether,  but  only  slightly  soluble  in  water.  It  is 
prepared  by  fusing  alpha-naphthalene  sulphonate  and 
caustic  soda,  decomposing  subsequently  with  hydrochloric 
acid  and  distilling.  It  is  used  in  making  dyestuffs. 

NAPHTHOL  (Beta)  (C10H17OH)  is  a  white,  lustrous  substance, 
soluble  in  benzol,  alcohol,  ether,  and  chloroform,  and 
slightly  soluble  in  water,  made  by  fusing  beta-naphthalene 
sulphonate  with  caustic  soda  and  subsequent  distillation.  It 
is  used  in  making  dyestuffs  and  as  an  antiseptic. 

NAPHTHYLAMINES  are  so-called  "intermediates"  for  dyes, and 
include  0-naphthylamine  (C10H7NH2),  a  colourless,  crystal- 
line compound  of  disagreeable  odour,  which  melts  at  50°  C., 
boils  at  300°  C.,  and  is  readily  soluble  in  alcohol ;  and 
i-naphthylamine  is  also  a  crystalline  compound  which 
melts  at  112°  C.,  boils  at  294°C.,  and  is  odourless. 

NARCEINE— See  Opium. 

NARCOTINE  (C22H23NO7)  (melting-point,  176°  C.)— A  crystal- 
line alkaloid  found  present  in  opium  to  the  extent  of  from 
about  2j  to  10  per  cent.  It  is  a  powerful  narcotic  poison, 
acting  like  morphine  on  the  sensory  cells,  although  less  de- 
cidedly, and  it  is  not  so  poisonous.  (See  Opium.) 

"NARKI"  METAL— A  proprietary  acid-resisting  silicon  cast 
iron  alloy  used  in  making  plant  for  concentration  of  sul- 
phuric acid,  acid  elevators,  pipes,  valves,  etc. 


NA  SCENT— NEPHRITE  329 

NASCENT — A  term  used  to  indicate  the  state  of  chemical  sub- 
stances at  the  moment  of  their  generation  or  formation, 
when  they  are  often  more  active  in  their  properties  than 
ordinarily.  Certain  experiments  have  been  recently  made 
which  show  that  the  chemical  affinity  of  such  gases  as 
hydrogen,  oxygen,  nitrogen,  or  carbon  monoxide  is  in- 
creased by  bringing  them  in  contact  with  solutions  in  very 
minute  bubbles,  as  obtained,  for  example,  by  forcing  these 
gases  through  cartridges  of  paper.  Hydrogen  was  thus 
proved  to  reduce  mercuric  chloride  to  calomel,  potassium 
nitrate  to  nitrite,  and  carbon  dioxide  to  formaldehyde. 
With  oxygen  gas,  ammonia  was  oxidized  to  nitrous  acid 
and  methyl  alcohol  to  formaldehyde  ;  while  with  nitrogen 
and  hydrogen  an  indication  of  the  production  of  ammonia 
was  observed. 

NATROLITE  —  A  crystalline  zeolite  mineral  (Na2Al2Si3O10, 
2H2O).  (See  Zeolites.) 

NATRON — A  crude  native  form  of  sodium  carbonate  found  in 
the  soda-lakes  of  Egypt,  Hungary,  Magadi,  and  elsewhere. 
(See  Sodium.) 

NEAT'S-FOOT  OIL — A  liquid  oil,  soluble  in  alcohol  and  ether, 
obtained  in  the  process  of  boiling  down  calves'  and  sheep's 
feet.  Sp.  gr.,  0*964  to  0-98  ;  saponincation  value,  70  to  75; 
iodine  value,  191  to  199  ;  and  refractive  index,  1*469.  It 
is  used  as  a  leather  dressing  and  lubricant. 

NECTAR — A  sugary  juice  which  collects  in  the  nectaries  or 
discs  of  flowers,  containing  cane  sugar  together  with 
uncrystallizable  sugar.  « 

NEODYMIUM  (Nd) — Atomic  weight,  144-3  5  SP-  gr->  6-9563. 
An  extremely  rare,  recently  discovered  element  belonging 
to  the  cerium  group,  which  has  been  isolated  by  the 
electrolysis  of  its  anhydrous  chloride.  It  has  a  melting- 
point  of  840°  C.  and  forms  salts  of  a  rosy  colour.  An 
oxide  (Nd2O3)  of  a  pale  blue  colour  is  known. 

The  hydroxide  (Nd(OH)3)  is  obtained  by  adding  alkali 
to  a  solution  of  its  salts;  and  the  chloride  (NdCl3), 
nitrate,  bromide,  and  iodide,  are  crystalline  soluble  salts. 

NEON  (Ne) — Atomic  weight,  20*2.  An  element  present  in  the 
air  to  the  estimated  extent  of  only  i  part  in  about  100,000. 
It  exhibits  a  characteristic  spectrum  and  has  been  liquefied. 
It  is  a  member  of  the  argon  group,  more  volatile  than  argon, 
and  exhibits  no  decided  chemical  characteristics. 

NEPHRITE — A  mineral  something  akin  to  jade.     (See  Jade.) 


330  NEROL— NICKEL 

NEROL  (C10H18O)— An  aromatic  alcohol  of  sp.  gr.  0-881 
isomeric  with  geraniol,  occurring  in  the  finer  extracts  of 
rose  and  neroli. 

NEROLI  OIL — A  reddish -yellow  essential  oil  distilled  from 
orange  flowers,  of  which  there  are  several  varieties  (Citrus 
aurantium  vulgaris,  etc.).  Sp.  gr.  about  0-87  to  0-88,  soluble 
in  alcohol,  ether,  etc.  Its  constituents  include  linalyl 
acetate,  linalool,  geraniol,  and  limonene.  (See  Linalool.) 

NESSLER'S  REAGENT  —  A  solution  of  mercuric  iodide  in 
potassium  iodide  made  alkaline  by  potassium  hydrate,  which 
turns  yellowish-brown  even  with  traces  of  ammonia,  for 
which  it  is  a  delicate  test. 

NEURINE  (C5H13NO  or  C5H15NO2)— An  amine  base  obtained 
from  brain-substance  and  bile,  and  which  upon  oxidation 
with  strong  nitric  acid  gives  muscarine  (C5H15NO3).  It 
is  nearly  related  to  choline. 

NEUTRALIZATION— The  removal  of  acidity  or  alkalinity  from 
a  solution  to  a  neutral  state  by.  means  of  an  alkaline  or  acid 
solution,  as  tested  by  litmus-paper. 

NICKEL  (Ni)  and  its  Compounds — Atomic  weight,  59  ;  sp. 
gr.,  8'8  ;  melting-point,  1,452°  C.  Nickel  occurs  in  com- 
bination in  a  number  of  minerals  (chiefly  in  combination 
with  arsenic)  as  kupfernickel  (Ni2As2),  white  nickel  (NiAs2), 
nickel  glance  (Ni2(AsS)2),  and  nickel  blende  (NiS)  ;  also  in 
association  with  cobalt  in  speiss.  Nickel  deposits  have 
recently  been  found  at  Blaaubank  and  in  the  Pelandsberg 
(Rustenberg)  district  of  South  Africa. 

It  can  be  obtained  by  heating  the  oxalate  of  nickel 
out  of  contact  with  air,  or  by  reduction  of  the  oxide  with 
carbon  at  a  high  temperature ;  but  is  now  made  commer- 
cially in  large  quantity  both  from  the  sulphide  ores  and  the 
mineral  garnierite — a  silicate  of  nickel  and  magnesium  found 
in  New  Caledonia  and  Oregon  (and  which  is  first  of  all 
converted  into  sulphide) — by  a  roasting  process,  in  which 
the  sulphur  and  arsenic  constituents  are  for  the  most  part 
burned  off,  the  resulting  mixed  metallic  oxides  being  sub- 
sequently heated  to  from  50°  to  80°  C.  in  a  stream  of  so- 
called  "producer  gas "  containing  carbon  monoxide.  (See 
Producer  Gas.)  By  this  process  they  are  reduced  to  the 
metallic  state,  other  than  the  nickel  ;  this  enters  into 
combination  with  the  carbon  oxide,  forming  nickel  carbonyl 
(Ni(CO)4),  which  passes  off  in  a  vaporous  state;  and 
from  this,  the  nickel  is  obtained  by  passage  of  the  gases 
through  a  pipe  heated  to  about  180°  C.,  whereby  the 


NICKEL— NICOTINE  331 

NICKEL  (Continued)— 

mixture  is  resolved  into  gaseous  carbon  oxide  (which  is 
used  over  again  in  fresh  operations),  the  free  metallic  nickel 
being  deposited  in  a  lustrous  mirror-like  form. 

There  is  also  an  electrolytic  process  of  preparing  nickel 
in  the  forn\of  cathode  sheets,  from  the  roasted  ore  after 
leaching  with  acid  to  remove  most  of  the  copper. 

In  the  free  elemental  state,  it  is  best  known  as  a  black 
powder,  but  it  can  be  obtained  in  the  metallic  state  and  is 
then  a  bright,  lustrous,  white,  ductile,  malleable  but  tenacious 
metal  of  very  hard  character  and  high  melting-point.  It  is 
used  chiefly,  amongst  other  applications,  for  toughening 
steel  and  in  the  manufacture  of  alloys  for  making  coins  in 
Germany,  Belgium,  France  and  the  United  States.  It  is 
also  extensively  used  for  plating  iron  and  steel  articles  (by 
reason  of  the  fact  that  it  does  not  readily  tarnish  in  the  air) 
and  as  a  catalyst  in  connection  with  a  number  of  processes, 
including  one  for  hardening  oils  by  hydrogenation.  (See 
Hydrogen,  p.  251.) 

Nickel  forms  two  oxides,  NiO  and  Ni2O3,  the  monoxide 
being  obtained  by  heating  the  nitrate  or  carbonate.  In  the 
form  of  nickelous  hydroxide  (Ni(HO)2)  it  is  obtained  by 
adding  an  alkaline  solution  to  one  of  a  soluble  nickel  salt, 
as  a  light  green  precipitate  which  upon  drying  and  heating 
becomes  anhydrous. 

There  is  also  a  soluble  chloride  (NiCl2),  a  nitrate 
(Ni(NO3)2),  and  a  sulphate  (NiSO4,7H2O),  which  crystallizes 
in  prisms,  all  of  which  are  green  in  colour  and  soluble 
in  water. 

Several  sulphides  are  known  ;  of  these,  nickel  monosul- 
phide  (NiS)  is  black  and  insoluble  in  water  and  dilute  acids. 

The  carbonate  (NiCO3)  (a  crystalline  compound  in- 
soluble in  water),  the  chloride,  the  cyanide  (Ni(CN)2-4H2O) 
(which  is  insoluble  in  water),  the  nitrate,  the  sulphate,  and 
the  double  sulphate  of  nickel  and  ammonium  (NiSO4. 
(NH4)2SO4.6H2O)  (which  is  soluble  in  water),  are  all  used 
in  nickel  plating,  whilst  the  chloride  is  also  used  in  the 
preparation  of  sympathetic  ink,  etc. 

Nickel  Carbonyl  is  a  colourless,  volatile  liquid  soluble 
in  alcohol,  of  sp.  gr.  1-3185,  which  boils  at  43°  C.,  and  its 
vapour  explodes  at  60°  C. 

The  compounds  of  nickel  impart  a  reddish-yellow  colour 
to  a  fused  bead  of  borax. 

NICOTINE  (C10H14N2) — An  oily,  colourless,  alkaloidal  liquid 
of  sp.  gr.  1-009,  constituting  the  acrid  basic  principle  of 


332  NICOTINE— NITRE  CAKE 

NICOTINE  (Continued)— 

tobacco,  in  which  it  is  found  present  in  amount  varying 
from  2  to  8  per  cent. 

Nicotine  is  not  present  in  the  seed  of  the  plants  but 
appears  in  the  young  plant  immediately  the  chlorophyll 
begins  to  function,  and  originates  in  the  leaf.  4 

It  is  soluble  in  water,  alcohol,  and  ether.  Preparations  of 
it  are  extensively  used  for  horticultural  purposes  as  an  in- 
secticide, also  as  a  dip  for  the  destruction  of  ticks  and  other 
pests  on  the  wool  of  sheep. 

NIGROSINES— A  class  of  black  dyes  prepared  by  heating 
aniline  and  its  hydrochloride  with  nitro-benzene  and  a 
metal.  They  are  of  various  solubilities — some  in  water, 
some  in  alcohol,  and  others  in  oil — and  are  used  in 
making  polishes,  varnishes,  inks,  and  in  the  dyeing  and 
leather  trades. 

NIOBITE — Another  name  for  the  mineral  columbite. 
NIOBIUM— See  Columbium. 

NITON  (Nt) — Atomic  weight,  222-4.  A  rare  mert  element  of 
recent  discovery,  being  a  radium  emanation  soluble  in  water, 
prepared  by  heating  a  radium  compound  or  by  dissolving 
it  in  water  and  pumping  off  the  gases  slowly  generated  from 
it,  and  from  which  it  is  obtained  by  first  of  all  removing 
any  associated  oxygen,  hydrogen,  carbon  dioxide,  and 
nitrogen,  thus  leaving  the  niton  (which  liquefies  at  from 
-  150°  to  -  170°  C.)  from  which  in  turn  the  generated  helium 
may  be  pumped  off.  It  can  be  condensed  to  the  solid  state, 
and  both  it  and  the  liquid  forms  are  phosphorescent.  It  is 
said  to  spontaneously  decompose  into  helium  and  other 
substances. 

NITRATES — See  Nitrogen  Compounds. 

NITRATION — A  term  given  to  a  chemical  process  by  which, 
using,  generally,  strong  nitric  acid,  the  nitro  group  (NO2) 
is  introduced  into  organic  compounds,  as  illustrated  by 
the  production  of  nitro-benzene  (C6H5NO2)  from  benzene 
(C6H6).  Again,  toluene  (C7H8)  can  by  the  action  of  strong 
nitric  acid,  be  converted  successively  into  mononitro- 
toluene  (C7H?NO2),  dinitro-toluene  (C7H6(NO2)2),  and  tri- 
nitro-toluene  (C7H6(NO2)3).  (See  Explosives.) 

NITRE— See  Potassium. 

NITRE  CAKE — See  Sodium  (Hydrogen  Sulphate). 


NITRIC  ACID— NITROGEN  333 

NITRIC  ACID — See  Nitrogen  and  Nitrogen  Fixation. 
NITRIC  ETHER— See  Ethyl  Nitrate. 

NITRIDES — Magnesium,  boron,  silicon,  titanium,  and  some 
other  elements  combine  with  nitrogen  at  a  red  heat  to  form 
nitrides,  and  these  are  decomposed  again  by  the  agency  of 
steam,  thus  yielding  ammonia.  Aluminium  nitride  is  now 
an  article  of  some  commercial  importance.  See  Aluminium 
(p.  24)  and  Chemical  Compounds  (p.  102). 

NITRIFICATION — A  process  by  which  ammonia  and  other 
nitrogenous  substances  present  in  soil  are  converted 
into  nitrates  by  the  action  of  micro-organisms.  Am- 
monium carbonate,  for  example,  is  first  of  all  oxidized 
and  converted  into  a  nitrite  by  the  agency  of  one  micro- 
organism, and  this  is  changed  by  another  micro-organism 
into  the  state  of  nitrate,  the  process  requiring  the  presence 
of  a  base.  It  is  known  that  the  presence  of  calcium  sul- 
phate (gypsum)  greatly  facilitates  the  nitrification  of  urine. 
Nitrifying  micro-organisms  exist  to  a  depth  of  about 
6  feet  in  soil,  but  nitrification  is  practically  confined  to  the 
surface,  air  being  essential  to  the  process.  The  purification 
of  sewage  by  filtration  through  soil  is  largely  due  to 
nitrification.  (See  Bacteria,  Soil,  and  Microbes.) 

NITRILES — Derivatives  of  hydrocyanic  acid,  the  hydrogen  in 
the  HCN  being  replaced  by  radicals — for  example,  aceto- 
nitrile  or  methyl  cyanide  (CH3.CN). 

NITRITES— See  Nitrogen. 

NITROGEN  and  its  Compounds  —  Nitrogen  (N)  —  atomic 
weight  14,  and  melting-point  -210°  C. — is  contained  in 
the  air,  of  which  it  makes  about  four-fifths,  while  in  com- 
bination, it  occurs  as  Chili  nitre  or  saltpetre  in  Chili,  Peru, 
and  elsewhere,  or  crude  sodium  nitrate  (NaNO3)  which 
is  largely  employed  as  a  nitrogenous  fertilizer  or  dressing 
for  agricultural  purposes.  It  is  also  found  in  combination 
as  potassium  nitrate  in  the  form  of  nitre  or  saltpetre  (KNO3) 
in  certain  soils  in  India  and  Ceylon,  and  as  a  constituent  of 
many  animal  and  vegetable  substances. 

It  can  be  obtained  in  quantity  by  the  liquefaction  of  air 
and  boiling  off  the  nitrogen  at  -  195*5°  C-  (See  Oxygen.) 

Nitrogen  can  be  readily  made,  in  the  laboratory,  from  the 
air  by  the  abstraction  of  the  oxygen — for  example,  by 
the  use  of  alkaline  potassium  pyrogallate  solution,  which 
has  a  great  affinity  for  oxygen,  speedily  absorbing  it  from 


334  NITROGEN  AND  ITS  COMPOUNDS 

NITROGEN  (Continued)— 

a  quantity  of  air  confined  in  a  closed  vessel,  and  leaving 
the  nitrogen  unabsorbed.  Similarly,  when  phosphorus  is 
burned  in  air  it  combines  with  the  oxygen  to  form  phos- 
phorus pentoxide,  leaving  nearly  pure  nitrogen. 

It  can  also  be  made  by  passing  a  stream  of  air  over 
metallic  copper  heated  to  redness,  when  the  oxygen  of 
the  air  combines  with  and  is  fixed  by  the  copper,  forming 
cupric  oxide,  and  nitrogen  gas  passes  over. 

Every  living  thing  contains  nitrogen,  which  is  a  colour- 
less gas  without  taste  or  smell,  nearly  insoluble  in  water 
(i  volume  of  which  at  o°  C.  dissolves  only  0^0235  volume 
of  the  gas),  and  in  its  free  state  is  what  is  termed  a  very 
inert  chemical  substance.  In  other  words,  it  is  very  inactive 
and  exhibits  but  little  tendency  to  enter  into  chemical 
combination  with  other  substances.  It  can,  however,  be 
prepared  in  a  much  more  chemically  active  (and  therefore 
probably  allotropic  (isotopic))  form  by  an  electrical  process  ; 
moreover,  in  combination  it  becomes  extremely  active. 

A  corona  discharge  at  20,000  volts  from  a  fine  wire  is 
stated  to  be  capable  of  transforming  4  per  cent,  pure 
nitrogen  into  its  activated  form,  and  in  this  state  it  will 
combine  with  hydrogen  to  form  ammonia,  with  oxygen  to 
form  oxides,  and  with  various  metals  to  form  nitrides. 
This  activated  nitrogen  is  more  stable  than  activated 
hydrogen,  and  persists  for  some  hours. 

It  exhibits  a  glow,  and  it  will  attack  acetylene  and  other 
gases  containing  carbon,  thus  producing  cyanogen  com- 
pounds. 

Ammonia  (NH3) — One  of  the  most  important  combina- 
tions of  nitrogen  is  ammonia,  the  salts  of  which  are  for  the 
most  part  obtained  from  the  ammoniacal  liquor  of  gasworks, 
for  which  purpose  the  gas  liquor  is  treated  with  lime  and 
distilled,  the  ammonia  being  thus  driven  over  and  condensed 
in  water,  or  passed  into  sulphuric  or  hydrochloric  acid, 
forming  respectively  ammonium  sulphate  ((NH4)2SO4)  or 
chloride  (NH4C1). 

A  process  (Cobb's)  recently  devised  for  recovering 
ammonia  from  coal  consists  in  washing  the  gas  in  a 
solution  of  zinc  sulphate,  thus  causing  the  precipitation 
of  zinc  sulphide,  accompanied  with  the  production  of 
ammonium  sulphate  in  solution.  The  zinc  sulphide  is 
filtered  off  and  roasted,  thus  producing  the  oxide  and 
sulphur  dioxide  gas,  and  by  suspending  the  oxide  in  water 
and  exposing  it  to  the  roaster  gas  zinc  sulphate  is  re- 
generated for  use  over  again. 


NITROGEN  AND  ITS  COMPOUNDS  335 

NITROGEN  (Continued)— 

The  ammonium  sulphate  is  recovered  from  its  solution 
by  evaporation. 

Ammonia  is  very  soluble  in  water,  which,  at  the  ordinary 
temperature  of  the  air,  absorbs  727  times  its  own  volume  of 
the  gas,  and  at  o°  C.  1,148  volumes.  The  solution  is 
colourless,  strongly  alkaline,  and  of  characteristic  pungent 
odour. 

Ammonia  has  been  produced  on  a  commercial  scale 
from  a  mixture  of  nitrogen  and  hydrogen  gases  contained 
under  pressure  and  exposed  to  a  high  temperature,  using 
a  catalytic  agent  to  effect  the  combination.  (See  Nitrogen 
Fixation.) 

The  ammonium  radical  (NH4)  which  is  capable  of 
replacing  an  atom  of  hydrogen  in  acids  has  not  been 
isolated. 

Ammonia  is  extensively  used  in  connection  with  re- 
frigerating appliances,  and  some  of  its  salts  for  rendering 
wood  and  other  materials  non-inflammable. 

In  1913  the  world's  ammonia  production  in  terms  of 
sulphate  amounted  to  1,389,790  tons,  the  essential  sources 
being  gasworks,  coke-ovens,  gas  producers,  shaleworks, 
ironworks,  and  bone  and  other  carbonizing  works. 

Ammonium  Sulphate  ((NH4)2SO4)  is  largely  used  as  a 
nitrogenous  fertilizer  for  agricultural  purposes  and  for  the 
manufacture  of  ammonia-alum  (see  Alums)  and  other  com- 
pounds. The  commercial  quality  of  sulphate  employed 
for  agricultural  use  contains  about  24^  to  25  per  cent, 
ammonia. 

In  1914  the  production  of  this  compound  in  the  United 
Kingdom  was  as  follows  : 

Gasworks 176,000  tons. 

Ironworks...         ...       16,000     „ 

Shaleworks  63,000     ,, 

Coke   and   carbonizing  and  pro- 
ducer gasworks  ...         ...  171,000     ,, 


Total          426,000  tons. 


Ammonium  Nitrate  (NH4NO3),  as  prepared  from  am- 
monia and  nitric  acid,  is  used  in  the  making  of  the  smokeless 
and  flameless  explosive  named  roburite. 

During  the  recent  war,  the  United  States  of  America 
produced  ammonium  nitrate  by  means  of  a  process  which 


336  NITROGEN  AND  ITS  COMPOUNDS 

NITROGEN  (Continued)— 

consisted  of  the  double  decomposition  of  Chili  saltpetre 
and  ammonium  sulphate  as  expressed  in  the  equation  : 

2NaNO3  +  (NH4)2SO4  =  2NaSO4  +  2NH4NO3. 
(See  Explosives.) 

Ammonium  Chloride,  as  prepared  from  gas  liquor,  is  puri- 
fied by  sublimation,  and  is  then  a  colourless,  crystalline 
substance,  soluble  in  cold  water  to  the  extent  of  about 
33  per  cent.,  and  is  known  commercially  by  the  name  of 
"sal-ammoniac."  It  is  manufactured  on  a  large  scale, 
being  used  in  medicine,  in  dyeing  operations,  in  electric 
batteries,  as  a  fertilizer,  in  galvanizing,  and  in  the  prepara- 
tion of  a  cement  for  fixing  iron  in  stonework  (made  of  iron 
filings  mixed  with  i  or  2  per  cent,  sulphur  and  moistened 
with  a  solution  of  the  sal-ammoniac). 

There  are  several  ammonium  carbonates,  including  the 
commercial  article,  which  is  made  by  heating  a  mixture  of 
ammonium  sulphate  and  ground  chalk  to  redness  and  con- 
densing the  generated  vapours.  It  is  a  mixture  of  ammo- 
nium hydrogen  carbonate  ((NH4)HCO3)  and  ammonium 
carbamate  ((NH4)(NH2)CO2) — from  which  the  carbamate 
can  be  washed  out  with  alcohol — and  has  a  strong  am- 
moniacal  odour. 

Ammonium  Carbonate  ((NH4)2CO?)  can  be  obtained  from 
the  commercial  compound  by  passing  ammonia  gas  into 
a  strong  solution,  but  upon  exposure  to  air  it  gives  off 
ammonia  and  is  changed  back  to  the  compound  NH4HCO3, 
a  body  which,  when  crystallized  in  a  pure,  dry  state,  does 
not  smell  of  ammonia. 

Ammonium  Phosphate  ((NH4)2HPO4) — A  white,  crystal- 
line salt,  soluble  in  water;  used  in  medicine,  fireproofing, 
etc. 

Sal- volatile  is  a  dilute  solution  of  ammonium  carbonate. 

There  are  a  number  of  other  ammonium  compounds 
used  commercially,  including  the  oxalate,  the  molybdate, 
the  perchlorate,  and  the  sulphocyanide.  Ammonium 
acetate  (NH4(C2H3O2))  is  used  medicinally  as  a  sudorific 
(Liquor  ammonii  acetici). 

Nitric  Acid  (HNO3)  is  a  very  important  nitrogen  com- 
pound, and  is  formed  in  a  variety  of  ways,  but  the  method 
by  which  it  is,  in  the  main,  commercially  produced  is  by 
the  action  of  sulphuric  acid  (H2SO4)  upon  sodium  nitrate 


NITROGEN  AND  ITS  COMPOUNDS  337 

NITROGEN  (Continued)— 

(NaNO3).     The  first  stage  of  the  process  is  represented  by 
the  equation : 

NaN03  +  H2S04  =  NaIiSO4  +  HNO3, 

and  by  pushing  the  heating  further  there  is  a  secondary 
change,  as  follows : 

NaNO3  +  NaHSO4  =  Na2SO4  +  HNO3. 

The  operation  is  generally  carried  out  in  cast-iron  eggs 
or  cylinders  lined  with  fireclay,  under  the  influence  of  heat, 
the  nitric  acid  passing  over  in  the  form  of  vapour,  which  is 
condensed. 

In  practice,  nearly  equal  parts  of  purified  Chili  nitrate  and 
sulphuric  acid  are  subjected  to  distillation,  and  the  strength 
of  the  acid  which  is  employed,  depends  upon  the  kind  of 
nitric  acid  that  is  required,  concentrated  sulphuric  acid  of 
about  1 60°  Twaddell  being  used  for  making  strong  nitric 
acid,  and  that  of  about  140°  Tw.  (ordinary  Glover  tower 
acid)  being  used  for  production  of  weak  nitric  acid. 

The  so-called  "  fuming  "  nitric  acid  contains  upwards  of 
86  per  cent.  HNO3,  and  has  a  specific  gravity  of  about 
1-48-  It  is  very  corrosive,  and  in  contact  with  many 
organic  substances  causes  their  combustion.  The  ordinary 
commercial  nitric  acid,  known  as  "aqua  fortis,"  contains 
about  65-5  per  cent.  HNO3. 

Nitric  acid  is  colourless  when  pure  and  is  a  strongly  fuming 
hygroscopic,  corrosive  liquid  with  a  sp.  gr.  of  1-53,  which 
attacks  many  metals  with  avidity  and  forms  by  combina- 
tion therewith  or  with  their  oxides,  a  large  number  of 
corresponding  nitrates. 

It  is  also  a  powerful  oxidizing  agent  and  its  uses  in- 
dustrial chemistry  are  many  and  of  great  importance,  in 
including  its  employment  in  the  manufacture  of  the 
explosives  nitro-glycerine,  gun-cotton,  etc.  (See  Explo- 
sives.) 

Nitrates  in  the  soil  are  produced  by  the  slow  oxidation  of 
ammonia  (derived  from  nitrogenous  animal  matter)  in  the 
presence  of  air  and  an  alkali,  and  this  process  probably 
accounts  for  the  natural  deposits  found  in  Chili  and  else- 
where. (See  Nitrification.) 

Nitrogen  Oxides — There  are  six  of  these,  having  the 
formulae  N2O,  NO,  N2O3,  NO2,  N2O4,  and  N2O5 ;  and 
there  are  three  acids  corresponding  respectively  to  the 
oxides  N2O,  N2O3,  and  N2O5. 

22 


338  NITROGEN  OXIDES 

NITROGEN  (Continued)— 

Nitrous  Oxide  (N2O),  known  also  as  laughing  gas,  can  be 
obtained  by  gently  heating  ammonium  nitrate,  when  it 
splits  up  into  N2O  and  water — 


or  by  heating  a  mixture  of  sodium  nitrate  and  ammonium 
sulphate  to  230°  C.  and  collecting  the  gas  over  mercury. 
It  is  a  colourless  gas,  soluble  in  water  to  the  extent  of 
I"3°5  volumes  of  the  gas  in  i  volume  of  water  at  o°  C.,  of 
a  faint  not  unpleasant  odour,  and  when  breathed  for  a  short 
time,  induces  excitement  and  in  some  cases  laughter.  It  is 
used  to  some  extent  as  an  anaesthetic  in  dentistry  and  is 
easily  liquefied  to  a  colourless,  mobile  fluid  which  can  be 
frozen  solid. 

Nitric  Oxide  (NO)  is  obtained  by  the  action  of  nitric  acid 
of  sp.  gr.  i  "2  upon  copper  or  mercury,  when  the  nitrate  of 
the  metal  passes  into  solution  and  the  gas  (NO)  is  generated. 
It  is  colourless  and  enters  into  combination  with  atmo- 
spheric oxygen  to  form  red-brown  irritating  vapours  of 
nitrogen  peroxide. 

Nitrogen  Trioxide  (N2O3)  is  made  by  exposing  a  mixture 
of  nitric  oxide  and  nitric  peroxide  to  a  temperature  of 
—  20°  C.,  when  it  is  produced  as  a  bluish-green  fluid. 

Nitrogen  Peroxide  (NO«)  can  be  prepared  by  passing  a 
mixture  of  2  volumes  or  nitric  oxide  with  i  volume  of 
oxygen  through  a  tube  surrounded  by  a  freezing  mixture. 
At  low  temperatures  it  is  a  colourless,  crystalline  compound 
which  melts  at  -  9°  C.,  and  at  higher  temperatures  it  takes 
on  a  yellow  and  then  an  orange  colour.  It  boils  at  22°  C. 
and  gives  off  reddish-brown  vapours;  in  fact,  it  is  dis- 
sociated as  the  temperature  rises,  and  at  140°  C.  it  is 
entirely  resolved  into  NO2  so  that  the  crystalline  substance 
from  which  it  is  produced  is,  for  various  reasons,  regarded 
as  having  the  constitution  represented  by  N2O4. 

According  to  a  recent  report,  an  investigation  made  on 
behalf  of  the  Medical  Research  Committee  has  provided 
evidence  that  the  so-called  "  active  oxygen "  of  fresh 
country  air  is  not  ozone  but  nitrogen  peroxide.  This, 
however,  cannot  be  regarded  as  proven,  for  although  it 
may  at  times  be  present  as  a  result  of  electrical  action  by 
lightning,  peroxide  of  hydrogen  is  more  often  present  as  an 
atmospheric  constituent  particularly  in  the  neighbourhood 
of  pine  woods.  (See  Hydrogen  Peroxide.) 

Nitrogen  Pentoxide  (N2O5)  is  a  white,  solid,  crystalline 


NITROGEN—  NITROGEN  FIXATION  339 

NITROGEN  (Continued)— 

substance  which  melts  at  30°  C.  with  partial  decomposition, 
and  when  suddenly  heated,  is  apt  to  explode  with  violence. 
Placed  in  contact  with  water,  it  produces  nitric  acid  — 


N205+H20 

It  can  be  prepared  by  withdrawing  the  elements  -of  water 
from  nitric  acid  by  means  of  phosphorus  pentoxide  — 

2HNO3  +  P2O5=  2HPO3  +  N2O5 

—  the  mixture  being  cautiously  made  and  kept  cool  at  first, 
and  then  gently  heated,  when  the  N2O5  distils  over  and  can 
be  condensed  in  a  refrigerated  receptacle. 

Hyponitrous  Acid  (H2N2O2)  is  an  unstable  substance  and 
has  no  commercial  importance. 

Nitrous  Acid  (HNO2)  is  not  known  in  the  pure  state,  but 
its  salts  (the  nitrites)  are  stable  compounds  and  can  be  pre- 
pared by  heating  the  nitrates  above  their  fusion-point, 
when  oxygen  is  given  off  and  the  nitrites  are  obtained  by 
this  reduction  ;  for  example  — 

KNO3=KN02  +  0. 

When  the  nitrites  are  subjected  to  the  action  of  dilute  acids 
they  are  decomposed,  brown  vapours  being  given  off, 
whereas  the  nitrates  are  stable  under  this  treatment. 

Nitrogen  Trichloride  —  Obtained  from  ammonium  chloride 
by  the  action  of  chlorine  — 


is  a  thin,  oily,  very  volatile  liquid  of  pale  yellow  colour  and 
sp.  gr.  1-65,  having  an  irritating  pungent  odour.  It  is 
one  of  the  most  dangerous  explosives,  decomposing  with 
great  violence  when  exposed  to  sunlight  or  brought  into 
contact  with  grease,  turpentine,  and  many  other  substances. 
There  is  a  corresponding  bromide  and  a  crystalline  iodide 
represented  by  the  formula  N2H3I3. 

NITROGEN  FIXATION—  Of  the  various  processes  for  the 
so-called  fixation  of  nitrogen,  some  depend  upon  the  direct 
union  of  nitrogen  with  oxygen  under  the  influence  of  the 
electric  arc  at  a  temperature  of  about  3,000°  C.,  but  these 
can  only  be  economically  carried  out  where  cheap  and 
abundant  supply  of  water-power  is  available  for  production 
of  the  requisite  electric  energy. 

When  a  current  of  air  is  passed  rapidly  through  the 
electric  arc,  nitrogen  peroxide   (NO2)   is   formed,  and   at 


340  NITROGEN  FIXATION 

NITROGEN  FIXATION  (Continued)— 

ordinary  temperatures  and  in  the  presence  of  water  this 
product  is  partially  convertible  into  nitric  acid. 

The  Hausser  process,  which  is  at  present  in  the  experi- 
mental stage,  is  one  in  which  the  heat  caused  by  the 
explosion  of  a  mixture  of  combustible  gas  and  air  is  used 
to  bring  about  the  union  of  nitrogen  and  oxygen,  oxides 
of  nitrogen  being  produced  which  can  be  absorbed  in  water 
whilst  power  is  generated  simultaneously. 

The  nitrous  gases  produced  by  these  methods  are  passed 
into  vertical  iron  cylinders  lined  with  acid-proof  stone  in 
which  the  nitric  oxide  previously  produced  is  oxidized  by 
atmospheric  oxygen  into  nitric  peroxide,  the  gases  being 
finally  condensed  by  contact  with  water  in  washing  towers 
into  nitric  acid. 

Nitric  acid  is  also  produced  to  some  extent  on  a  com- 
mercial scale  by  the  oxidation  of  ammonia,  and  there 
are  considerable  expectations  based  upon  this  method  of 
production  by  catalytic  agents,  including  platinum  gauze. 
In  this  process,  a  mixture  of  air  and  ammonia,  containing 
about  10  per  cent,  of  the  latter,  is  passed  through  platinum 
gauze  placed  between  washers  of  asbestos  board  or  nickel- 
chrome  sheet,  heated  in  the  first  place  by  a  plumber's  blow- 
pipe, but  maintained  subsequently  at  a  cherry-red  heat  by  the 
chemical  change  which  is  involved. 

The  Haber  process,  which  was  in  use  in  Germany  before 
the  war,  is  based  upon  the  direct  union  of  nitrogen  and 
hydrogen  at  a  temperature  of  from  500°  to  700°  C.,  main- 
tained by  means  of  an  electric  coil  and  under  a  pressure 
of  approximately  200  atmospheres,  in  the  presence  of  a 
catalyst,  thus  producing  ammonia,  which  can  be  subse- 
quently converted  into  nitric  acid  and  ammonium  nitrate 
by  oxidation,  or  into  ammonium  sulphate.  Metallic 
osmium  has  been  found  to  serve  well  as  a  catalyst  but  is 
too  expensive  for  use  on  a  manufacturing  scale,  and  an 
activated  iron  catalyst  such  as  ferro-molybdenum  is 
employed  in  practice. 

In  the  Claude  process,  nitrogen  boiled  off  from  liquefied 
air  is  admixed  with  hydrogen  gas  in  suitable  proportions 
and  the  mixed  gases  subjected  as  in  the  Haber  process  but 
under  a  greatly  increased  pressure — up  to  from  900  to  1,000 
atmospheres ;  so  that  whereas  in  the  Haber  process  only 
from  about  10  to  12  per  cent,  of  the  gases  is  transformed 
into  ammonia,  from  30  to  36  per  cent,  transformation  is 
effected,  and  the  product  is  obtained,  owing  to  the  great 
pressure,  in  liquid  form. 


NITROGEN  FIXATION-NITRO-PHENOLS  34' 

NITROGEN  FIXATION  (Continued)— 

The  ammonia  can  be  oxidized  by  air  on  the  surface  of  a 
solid  catalyst  such  as  platinum  wire  gauze  or  ferric  oxide 
at  a  temperature  of  about  650°  to  700°  C.,  the  main  re- 
actions being  as  follows  : 


4NH3  +  5O2=  4NO  +  6H2O, 

the  nitric  oxide  thus  produced  being  converted  into  nitric 
acid  by  means  of  atmospheric  oxygen  and  water  —  4NO  + 
3O2  +  2H2O  =  4HNO3.  For  this  purpose  the  gases  issuing 
from  the  converter  in  which  the  nitric  oxide  is  produced 
are  cooled  to  about  30°  C.  and  then  passed  into  the  oxida- 
tion and  absorptive  towers. 

It  is  stated  that  one  plant  at  Hochst  (Germany)  for  the 
oxidation  of  ammonia  into  nitric  acid  is  capable  of  pro- 
ducing the  equivalent  in  nitric  acid  of  6,500  tons  and 
another  of  10,000  tons  nitrate  of  sodium  per  month.  (See 
also  Cyanamide.) 

NITROGEN  TRICHLORIDE—  See  p.  339. 

NITRO-BENZENE,  or  OIL  OF  MIRBANE  (C6H5(NO2)),  is  a 
yellowish  liquid  of  sp.  gr.  1*1986  and  boiling-point  about 
211°  C.,  prepared  from  benzene  by  the  action  of  a  mixture 
of  sulphuric  and  nitric  acids,  and  can  also  be  produced 
by  the  action  of  strong  nitric  acid  on  turpentine.  It  has 
an  intense  odour  of  oil  of  bitter  almonds,  is  soluble  in 
alcohol  and  ether,  and  is  much  used  in  perfumery  and  as 
a  flavouring  principle,  also  in  the  dye  industry. 

There  are  several  di-nitro-benzenes  (C6H4(NO2)2)  and 
tri-nitro-benzenes  (C6H3(NO3)3)  respectively. 

NITRO-CALCITE  —  Native  calcium  nitrate. 
NITRO-CELLULOSE—  See  Explosives. 
NITRO-  GLYCERINE—  See  Explosives. 
NITRO-HYDROCHLORIC  ACID  —  See  Aqua  Regia. 
NITRO-LIME  (Calcium  Cyanamide)  —  See  pp.  77  and  148. 

NITRO  -PHENOLS  (Ortho,  Meta,  and  Para  Compounds) 
(C6H4OH.NO2)  are  all  crystalline  substances  soluble  in 
alcohol  and  ether,  the  meta  compound  being  used  for 
manufacturing  the  dyes  known  as  "rhodamines"  (which 
are  closely  allied  to  fluorescein)  whilst  the  para  compound 
is  used  in  making  phenacetin,  etc.  The  ortho  compound 
is  yellow  and  melts  at  45°  C.  ;  the  meta  compound  is  also 


342  NITRO-PHENOLS—NOTA  TION 

NITRO-PHENOLS  (Continued)— 

yellow  and  melts  at  96°  C.,  whilst  the  para  compound  is 
colourless  and  melts  at  114°  C. 
(For  Tri-nitro-phenol  see  p.  190.) 

NITRO-TOLUENES  (CH3.C6H4.NO2)— A  class  of  compounds 
produced  by  the  nitration  of  toluene.  The  para  compound 
is  a  solid,  crystalline  body  employed  for  making  fuchsine 
and  other  dyes  in  common  with  the  ortho  compound,  which 
is  a  liquid  substance  and  can  be  used  in  common  with 
nitro-benzene  in  preparing  so-called  "oil  of  mirbane." 

The  para  compound  melts  at  51°  C.  and  boils  at  234°  C., 
whilst  the  ortho  compound  boils  at  218°  C. 

(For  Tri-nitro-toluene  see  p.  191.) 

NITROSO  COMPOUNDS  contain  the  nitroso  group  N:O  ;  for 
example,  nitroso-benzene  (C6H5,N:O). 

NITROUS  ACID— See  p.  339. 

NITROUS  ETHER  (Ethyl  Nitrite)  (C2H5(NO2))  or  SWEET 
SPIRIT  OF  NITRE — A  drug,  used  as  a  diuretic  and  stimu- 
lant, prepared  by  the  action  of  nitric  acid  upon  alcohol. 

It  is  a  yellowish,  aromatic,  volatile,  and  inflammable 
liquid  of  sp.  gr.  0*900,  boiling  at  i6'4°  C.,  soluble  in  alcohol 
and  ether. 

NITROUS  OXIDE  (Laughing  Gas) — See  Nitrogen,  p.  338. 

NOMENCLATURE — The  terms  and  names  used  to  identify  and 
classify  chemical  substances.  (See  Chemical  Compounds, 
Chemical  Interactions,  and  Elements  ;  also  "  Hypo.") 

NORDHAUSEN  ACID — Fuming  concentrated  sulphuric  acid 
originally  prepared  at  Nordhausen  in  Saxony  by  the  dis- 
tillation of  ferrous  sulphate,  the  gas  generated  in  this  way 
being  condensed  in  ordinary  sulphuric  acid. 

It  really  consists  of  a  mixture  of  sulphuric  acid  (H2SO4) 
and  sulphur  trioxide  (SO3).  (See  Oleum  and  Sulphur 
Compounds.) 

NORMAL  STANDARD  SOLUTIONS— Contain  an  equivalent 
weight  of  the  substance,  dissolved  in  i  litre  (1,000  c.c.), 
and  deci-normal  solutions  are  of  one-tenth  that  strength  ; 
both  are  used  in  "  Volumetric  Analyses." 

NOTATION — The  use  of  symbols  and  formulae  to  denote  the 
constitution  of  chemical  substances.  (See  Chemical  Com- 
pounds, Chemical  Interactions,  and  Elements.) 


NOVOCAINE— NUTMEG  OILS  343 

NOVOCAINE  (or  =  p.  Amino  -  benzoyl  -  diethylamino  -  ethanol 
Hydrochloride,  NH2.C6H4.CO.O.C2H4.N.(C2H5)2HC1)— A 
complicated  organic  substance  used  as  a  local  anaesthetic  in 
place  of  cocaine,  being  less  toxic. 

NTJCLEINS  (Nucleo -Proteins) — Albuminous  substances  con- 
tained in  many  animal  and  vegetable  tissues. 

"  NULOMOLINE  " — A  proprietary  article  used,  for  some  pur- 
poses, as  a  substitute  for  glycerine,  being  a  solution  of 
partly  inverted  sugar  of  sp.  gr.  1-4. 

NUT  OILS — Include  many  varieties,  the  more  important  of 
which  are  described  under  their  several  names.  Palm 
kernels  contain  about  50  per  cent,  by  weight  of  a  white, 
solid  fat,  which,  after  refining,  is  used  in  making  margarine, 
and  the  residual  cake  or  meal  resulting  from  the  crushing 
and  extraction  of  the  oil  is  a  serviceable  cattle  food. 
Ground-nuts  or  earth-nuts  contain  from  about  35  to  40 
per  cent,  of  a  liquid,  palatable  oil,  and,  when  freed  from 
the  husks,  about  45  per  cent,  of  the  oil.  The  residual 
cake  is  highly  albuminous,  that  from  the  decorticated  seed 
sometimes  testing  above  50  per  cent.,  and  is  much  relished 
by  cattle.  Hazel  nuts  yield  60  per  cent,  of  a  pale  yellow 
oil,  and  walnut  oil  (formerly  called  "  nut  oil ")  from  the 
kernel  oijuglans  regia,  is  a  quick-drying  oil,  which  is  green 
when  freshly  extracted ;  it  turns  yellow  on  keeping,  is 
inodorous,  and  used  in  painting.  Walnuts  yield  as  much 
as  from  50  to  65  per  cent,  of  this  oil,  which  forms  a  soft  soap 
when  saponified  with  potash.  Almond  nuts  contain  about 
55  per  cent,  fat ;  beech  nuts,  57  per  cent. ;  brazil  nuts, 
66  per  cent. ;  cocoa-nuts,  from  50  to  55  per  cent.  ;  filberts, 
65  per  cent. ;  hickory  nuts,  67  per  cent. ;  pea-nuts,  39  per 
cent.  ;  pistachio  nuts,  51  per  cent. ;  and  pecan  nuts,  70  per 
cent. 

"  Nut  Oil  "  (arachis  oil,  pea-nut  or  ground-nut  oil)  is  now 
largely  produced  in  both  China  and  Japan  (particularly  in 
the  Yokohama  district),  also  in  Senegal,  and  should  not  be 
confounded  with  true  walnut  oil,  which  was  wont  to  be 
described  as  "  nut  oil."  (See  Arachis  Oil.) 
NUTMEG-  OILS — The  wild  oil  nutmegs  of  Myristica  sebifera, 
abundant  in  South  America,  yield  about  26  per  cent,  of  oil 
of  yellowish  colour  and  sp.  gr.  0-870  to  0-925,  soluble  in 
alcohol,  which  can  be  expressed  and  used  for  soap  and 
candle  making.  Nutmegs  are  also  used  as  a  condiment  in 
cooking  and  in  the  preparation  of  mace. 

Nutmegs  are  grown  in  the  Molucca  Islands  and  are  also 
cultivated  in  Java,  Sumatra,  Singapore,  etc, 


344  NUTMEG  OILS— OCCLUSION 

NUTMEG  OILS  (Continued)— 

The  oil  contains  a  narcotic  body  named  myristicin 
(C12H1403). 

The  kernels  of  the  Otoba  nutmeg  (Myristica  otaba),  from 
Colombia,  are  stated  to  yield  7-2  per  cent,  of  a  colourless, 
volatile  oil,  of  sp.  gr.  0*894  optical  rotation  +79*55,  and 
refractive  index  1-502 ;  soluble  to  the  extent  of  16  volumes 
in  90  per  cent,  alcohol  at  15 3  C. 

NUTRITION— See  Foods. 

NUX  VOMICA — The  dried  seeds  or  beans  of  a  species  (Sir.  Nux 
vomica)  of  apocynaceous  plants,  which  grow  in  Southern 
Asia  and  Northern  Australia,  and  yields  the  two  bases 
strychnine  (C21H22N2O2)  and  brucine  (C23H26N2O4). 
Strychnine  is  also  obtained  from  the  Sty.  Colubrina"tree 
(which  grows  in  the  Moluccas  and  yields  so-called  snake- 
wood)  and  from  the  Str.  S.  Ignatii  and  5.  Tieute.  (See 
Strychnine.) 

OAK  BABE  (from  Quercus  vobur) — See  Tannin  and  Gall  Nuts. 

OBSIDIAN — A  dark  green  or  jet  variety  of  lava,  containing  the 
oxides  of  aluminium,  magnesium,  potassium,  sodium,  and 
silica.  (See  Pumice.) 

"  OBSIDIANITE  " — A  proprietary  brand  of  fire  and  acid  proof 
material  for  use  in  the  construction  of  "Glover  "  and  "  Gay 
Lussac  "  towers.  (See  Sulphuric  Acid.) 

OCCLUSION — The  property  exhibited  by  certain  metals,  of 
absorbing  or  occluding  gases  when  exposed  to  them  in  a 
heated  condition.  The  behaviour  of  the  metals  platinum 
and  palladium  in  this  respect  is  referred  to  more  par- 
ticularly under  those  headings,  and  in  a  fine  state  of 
division,  gold,  iron,  nickel,  copper,  aluminium,  and  lead 
will  all  absorb  more  or  less  hydrogen  gas.  Iron  also 
occludes  carbon  monoxide,  and  melted  silver  is  capable  of 
occluding  oxygen  gas  when  in  a  molten  condition. 

Apart  from  the  increase  in  volume,  there  is  no  change  in 
the  appearance  of  the  metals,  but  their  density  is,  of  course, 
diminished  proportionately. 

In  view  of  recent  investigations  concerning  atomic  struc- 
ture and  the  transformation  of  the  chemical  elements,  it 
would  seem  of  importance  to  ascertain  whether  the  gases 
absorbed  by  metals  as  described,  differ  in  any  physical  or 
chemical  qualifications  from  those  originally  exposed  to 
their  action. 

In  the  Faraday  Lecture  delivered  by  Theodore  William 


OCCLUSION— ODOUR  THEORY  345 

OCCLUSION  (Continued)— 

Richards  to  the  Chemical  Society  in  ign,  it  was  pointed 
out  that  such  porosity  as  occurs  in  rigid,  compact  solids, 
usually  permits  the  passage  only  of  substances  which  enter 
into  the  chemical  structure  of  the  solids  themselves.  Thus, 
nitrogen  cannot  free  itself  from  imprisonment  within  hot 
cupric  oxide,  although  oxygen  can  escape  ;  again,  water 
cannot  evaporate  into  even  the  driest  of  atmospheres  from 
accidental  incarceration  in  crystals  lacking  water  of  crys- 
tallization. Palladium,  on  occluding  hydrogen,  is  obliged 
to  expand  its  bulk  in  order  to  make  room  for  even  this 
small  addition  to  its  substance.  The  behaviour  of  platinum, 
nickel,  and  iron  is  probably  analogous,  although  less 
marked.  Fused  quartz,  impermeable  when  cold,  allows  of 
the  passage  of  helium  and  hydrogen  at  high  temperatures ; 
but  most  other  gases  seem  to  be  refused  admission,  and 
very  many  solid  substances  appear  to  act  as  effective 
barriers  to  the  passage  of  even  hydrogen  and  helium, 
especially  when  cold ;  and  he  concludes,  from  a  review  of 
the  available  evidence,  that  interstices  between  atoms  in 
solids  and  liquids  must  be  extremely  small  in  proportion  to 
the  size  of  the  atoms  themselves,  while  he  raises  the 
question  if  there  are  any  interstices  at  all  (see  Ether 
and  Porosity).  He  believes  that  atoms  are  compressible 
throughout  their  whole  substance — i.e.,  they  may  contract 
or  expand,  or  vibrate  within  themselves,  even  when  they 
are  so  closely  packed  together  as  to  prevent  their  surfaces 
from  moving.  (See  Platinum  and  Palladium.) 

OCHRE — A  name  given  to  a  large  number  of  metallic  oxides 
— yellow,  red,  and  brown — found  naturally  in  a  more  or 
less  pulverulent  form,  such  as  iron  or  red  ochre  and 
molybdic  ochre. 

"  Yellow  ochre  "  is  a  clay  coloured  with  ferric  oxide. 

OCTYL  ALCOHOL  (C8H18O)— See  Alcohols. 
OCTYLENE — See  defines  and  Hydrocarbons. 

ODOUE  THEORY— The  so-called  " residual  affinity"  theory 
of  the  cause  of  odour,  rests  upon  the  view  that  it  arises 
from  the  free  or  unsatisfied  affinity  of  the  constituent 
molecule. 

To  have  an  odour,  a  substance  must  possess  this  residual 
or  unsatisfied  affinity,  be  sufficiently  soluble  in  the  water 
and  the  lipoid  fats  of  the  nose,  and  must  be  volatile. 

Unsaturated  bodies,  generally,  have  distinctly  stronger 
odours  than  saturated  ones. 


346  (EN A  NTH  1C  ETHER— OILS 

(ENANTHIC  ETHER  (Cognac  Oil)  (C9H18O2)  —  A  mobile 
liquid  substance  used  in  the  preparation  of  artificial  cognac 
and  for  flavouring  wines ;  made  from  oenanthic  acid  and 
ethyl  alcohol  by  the  action  of  sulphuric  acid,  and  prepared 
commercially  from  the  oxidized  products  of  oil  of  rue. 
It  is  stated  to  be  a  mixture  of  capric  and  caprylic  acids, 
has  a  strong  vinous  odour,  and  is  readily  soluble  in  alcohol 
and  ether.  Many  fusel  oils  contain  these  acids,  and  some 
Hungarian  wines  are  known  to  contain  amyl  caprate. 

OIL  CAKE — The  cake  remaining  after  the  expression  of  oils 
from  seeds. 

Home -manufactured  Cakes  and  Meals. — Linseed  cake  con- 
taining not  less  than  8  per  cent,  oil,  cotton-seed  cake, 
undecorticated  ground-nut  cake,  semi-decorticated  ground- 
nut cake,  decorticated  ground-nut  cake,  palm-kernel  cake, 
rape  cake,  copra  cake,  sesame  cake,  soya  cake,  extracted 
palm-kernel  meal,  extracted  rape  meal,  extracted  soya  meal. 
Imported  Cakes  and  Meals. — North  American  linseed 
cake,  Argentine  linseed  cake,  Canadian  linseed  cake, 
Australian  linseed  cake,  Spanish  and  Portuguese  linseed 
cake,  Egyptian  cotton-seed  cake,  decorticated  cotton-seed 
meal,  decorticated  cotton-seed  cake,  re-pressed  cotton  cake, 
semi-decorticated  cotton  cake,  copra  cake,  palm-kernel 
cake,  Rangoon  rice  meal,  Italian  rice  meal,  Canadian  rice 
meal,  Egyptian  rice  meal,  gluten  feed,  maize-meal  cake. 

The  feeding  values  of  cakes  are  chiefly  represented  by 
their  protein  constituents. 

"  OILDAG  "—See  Lubricants. 

OIL  OF  VITRIOL — Strong  sulphuric  acid  (about  98  per  cent, 
strength). 

OILS — There  are  oils  of  many  kinds,  but  they  may  be  roughly 
divided  into  three  classes — viz.,  the  essential  oils,  which 
are  described  under  that  heading  and  their  own  names,  and 
are  for  the  most  part  hydrocarbons  ;  the  petroleum  and 
paraffin  class,  derived  from  natural  deposits  or  distillation 
of  coal,  lignite,  wood,  peat,  etc.,  which  are  also  hydro- 
carbons but  of  another  class  ;  and  fat  or  fixed  oils,  derived 
from  animals,  vegetables,  or  fishes,  which  are  obtained 
either  by  pressing  the  nuts,  seeds,  or  organs  of  the  fishes 
which  contain  them,  or  extracting  them  with  solvents, 
and  the  more  important  ones  are  described  under  their 
several  names.  They  are  all  greasy  in  character  and  can 
be  made  into  soaps  by  saponification.  By  a  new  process, 
crushed  seeds  are  subjected  to  dry  heat  and  agitation, 
whereby  all  moisture  is  driven  off  and  the  meal  is  converted 


OILS 


347 


OILS  (Continued) — 

into  a  sloppy  state,  and  then  centrifugalized  at  the  same 
temperature.  In  this  way  50  to  75  per  cent,  of  the  oil 
content  can  be  extracted,  so  that  half  of  the  usual  pressing 
or  other  plant  is  required  to  complete  the  extraction. 

APPROXIMATE  TYPICAL  VALUES  OR  CONSTANTS  OF  OILS. 


Name. 

Sp.  Gr.  at 
15°  C. 

Saponifi- 
cation 
Value. 

Iodine 
Value. 

Refractive 
Index. 

Melting- 
Point. 

Arachis 

0-917-0-925 

185-196 

92-IOI 

I  '4705-1  -4745 

-8°C. 

Almond 

0-9175-0-9195 

189-192 

93-101 

1-473 

-  10°  C. 

(about) 

Candle-nut... 

0-925-0-927 

190-195 

136-140 

i8°C. 

Castanha    ... 

0-918 

193  '5 

1  06 

0-4°  C. 

Castor 

0*95-0-96 

176-183 

83-86 

1-480 

Cocoa-nut  ... 

0-9115 

250-258 

8-9 

1-4566 

20°-28°  C. 

Cohune 

0-868 

252 

11-13-7 

i8°-2o°  C. 

Cotton-seed 

0-922-0*927 

193-195 

108-116 

i'457 

Hempseed  ... 

0-925-0-928 

192-193 

148 

1-448 

Linseed 

0-932-0-938 

188-195 

185-195 

1-466 

Maize 

0-92-0-93 

188-193 

111-123 

Olive 

0-916-0-918 

185-196 

79-93 

1-469 

Palm  (butter) 

0-92-0-93 

2O2 

5i  '5 

27°-42°C. 

Palm(nutoil) 

0-952 

247-6 

13*5 

26°-30°C. 

Poppy-seed 

0-925-0-926 

193-195 

131-141 

1-457 

Rape-seed  ... 

0-916-0-917 

170-179 

96-100 

1-472-1-475 

I7°-22°  C. 

Sesame 

0-921-0-925 

188-193 

103-108 

i  '457 

26°-32°C. 

Soya-bean  ... 

0-936-0-940 

I92-20O 

137-141 

1-476 

220-3I°C. 

Sunflower  ... 

0-924-0-926 

189-193 

129-132 

1-461 

Tea-seed     ... 

0-916-0-919 

193-4-194 

81-7-82-3 

z'47-1'471 

Tung 

0-936-0-943 

190-195 

150-165 

1-503 

Walnut 

0-92-0-93 

192-197 

142-146 

i  -4804 

Neat's-foot 

0-964-0-98 

70-75 

191-199 

1-469 

Nut    oil     of 

commerce 

0-916-0-9185 

80-6-96-84 

1-4715-1-473 

Cod-liver   ... 

0-92-0-93 

171-189 

150-167 

1-479-1-483 

Dugong      ... 

0-92 

i97"5 

66-6 

Herring 

0-92 

180-194 

130-142 

Porpoise     ... 

0-926 

195-256 

88-119 

Sardine 

0-93 

190 

180-193 

1-48 

Seal 

0-924-0-926 

189-196 

127-159 

1-474 

Sperm 

(whale)    ... 

0-925 

188-193 

1  20 

1-46-1-47 

Tuna 

156 

The  fatty  or  fixed  oils  are  again  roughly  divisible  into 
two  classes  known  as  drying  and  non-drying.  The  former, 
such  as  linseed,  hemp,  and  poppy  oils,  readily  absorb 


348  OILS—OLEFINES 

OILS  (Continued)— 

oxygen  from  the  air,  thus  forming  a  skin  and  gradually 
drying  up,  whilst  the  latter  class  (including  almond,  olive, 
and  castor  oils)  do  not  so  pronouncedly  dry  up  in  this  way. 
(See  Essential  Oils,  Fats,  and  Petroleum.) 

Polymerization  is  most  easily  observed  with  highly  un- 
saturated  oils,  such  as  tung  and  linseed  oils,  but  is  not 
altogether  peculiar  to  them.  It  is  shown  by  gelatinization 
and  by  increase  in  density,  viscosity,  and  mean  molecular 
weight,  and  a  decrease  in  the  iodine  value. 

OILS  (Hydrogenation  of) — See  Hydrogen,  p.  252. 

"OKOL"  —  A  disinfectant  and  larvicide,  consisting  of  an 
emulsion  of  phenoloids ;  miscible  with  water. 

OLEFIANT  GAS— See  defines. 

OLEFINES — A  class  of  unsaturated  hydrocarbons  of  ascend- 
ing boiling-points  and  general  formula  C«H2«,  from  which 
the  glycols  are  derived,  including — 

Ethylene  (C2H4)     of  boiling-point  -  102-5°  c- 

Propylene  (C3H6)  „  -48°C. 

Butylene  (C4H8)  „  -  5°  C. 

Amylene  (C5H10)  „  +39°C. 

Hexylene  (CgH12)  „  68°  C. 

Heptylene  (C7H14)  „  95°  C. 

Octylene  (C8H16)  „  124°  C. 

etc. 

The  first  three  members  of  the  group  are  colourless 
gases,  and  when  the  liquid  members  are  reached  (with 
amylene)  they  diminish  in  mobility,  while  the  higher  ones, 
like  cerotine  (CgjH^)  and  melene  (C^H^),  are  solid,  and 
similar  to  paraffin.  These  last-named  substances  can  be 
obtained  from  china  wax  and  beeswax  respectively  by 
distillation. 

Most  of  them  are  soluble  in  alcohol  and  ether,  but  not 
in  water.  The  best  known  member  of  the  series  is 
ethylene  or  olefiant  gas,  and  is  prepared  by  the  action 
of  sulphuric  or  syrupy  phosphoric  acid  upon  its  corre- 
sponding alcohol  (C2H6O)  by  the  abstraction  of  water — 

C2H60  =  C2H4+H20, 

or  by  passing  carbon  monoxide  and  hydrogen  over  finely 
divided  platinum  or  nickel  at  100°  C.  It  is  one  of  the 
products  of  the  distillation  of  wood  and  coal  and  enters  in 


OLE  FINES— OLIVE  OIL  349 

OLEFINES  (Continued)— 

small  proportion  into  the  composition  of  coal  gas.  It  is 
but  slightly  soluble  in  water  and  alcohol,  burns  with  a 
luminous  flame,  and  was  used  in  preparing  mustard  gas. 
(See  Gassing.) 

By  combination  with  chlorine,  ethylene  forms  ethylene 
dichloride  (C2H4C12).     (See  Hydrocarbons.) 

OLEIC  ACID  (Ci8H34O2)  in  combination  with  glycerine  (as 
olein)  is  contained  in  most  fats  and  fixed  oils,  particularly 
the  latter,  and  when  pure  is  a  tasteless,  odourless,  crystalline 
body,  of  sp.  gr.  0-8908,  which  melts  at  14°  C,  and  is  very 
soluble  in  alcohol  and  ether.  It  absorbs  oxygen  from  the 
air  and  turns  yellow  upon  exposure.  Upon  saponification 
with  alkalies  it  yields  combinations  in  the  nature  of  soft 
soap.  The  natural  oils  containing  olein  belong  to  the 
"  non-drying  "  class — that  is  to  say,  they  do  not  thicken, 
and  more  or  less  dry  up  upon  exposure  to  the  air. 

Nitrous   acid   converts  oleic   acid   into   a  solid   stereo- 
isomeric  modification  known  as  elaidic  acid. 

OLEIN — The  glyceride  of  oleic  acid,  being  an  oily  body  found 
present  in  many  natural  fats,  and  which  yields  oleic  acid  (a 
fatty  acid)  and  glycerine  upon  hydrolysis.  (See  Fats.) 

"  OLEO  " — The  fluid  oil  otherwise  known  as  "  premier  jus," 
expressed  from  beef-fat,  and  used  in  making  "  margarine." 

OLEO  MARGARINE — Another  name  for  margarine. 
OLEO-RESINS — See  Balsams,  Gums,  and  Resins. 
"  OLEOSOL  "—See  Lubricants. 
OLEUM — See  Sulphur  (sulphuric  acid). 

OLIBANUM — A  gum  resin  used  as  incense,  obtained  from  a 
tree  of  the  terebinthaceous  order  growing  in  Arabia. 

OLIVE  OIL — An  oil  expressed  from  the  fruit  of  the  olive-tree 
(Oka  Europea),  extensively  grown  in  Southern  Europe,  and 
of  great  value  as  a  food  and  for  the  manufacture  of  certain 
kinds  of  soaps.  The  pure  oil  is  of  a  pale  yellow  or  greenish- 
yellow  colour  and  agreeable  taste,  has  a  sp.  gr.  of  0-916 
to  0-918,  a  saponification  value  of  185  to  196,  and  an 
iodine  value  of  79  to  93.  It  contains  about  75  per  cent, 
of  glycerides  (glyceral  esters  of  palmitic,  stearic,  and  oleic 
acids,  chiefly  oleic). 

It  has  recently  been  ascertained  that  when  olive  oil  is 
heated  with  mannitol  in  the  presence  of  a  small  amount  of 


350  OLIVE  OIL— OPIUM 

OLIVE  OIL  (Continued)— 

sodium  ethylate  the  glycerol  (glycerine)  can  be  replaced 
by  it,  and  the  product  is  far  superior  in  all  respects  to 
the  original  olive  oil  as  a  food  fat.  (See  Mannite.) 

OLIVENITE — A  native  arsenateof  copper  (4CuO.  As2O6  +  H2O). 

OLI VINE — A  mineral  magnesium  silicate  with  varying  amounts 
of  ferrous  silicate  ((MgFe)2SiO4). 

ONION  OIL — A  yellowish  liquid  of  penetrating  odour  and 
sp.  gr.  about  1*04,  containing  allyl  compounds,  used  in 
flavouring. 

Garlic  oil  contains  allyl  sulphide  ((C3H5)2S). 

ONYX  or  CHALCEDONY — A  native  coloured  form  of  nearly 
pure  silica  (a  chalcedonic  variety  of  quartz).  (See  Silica.) 

OOLITE — Varieties  of  limestone  rocks. 

OPAL — An  uncleavable  variety  of  colloidal  quartz.  (See  Silica.) 

OPAQUE — Not  transparent. 

OPIUM — The  dried  juice  extracted  from  the  seed  vessels  of  the 
poppy  (Papaver  somniferum),  containing,  amongst  other  sub- 
stances, several  alkaloids,  including  about  from  10  to  18  per 
cent,  of  morphine  (C17Hj9NO3.H2O) — a  powerful  drug 
used  medicinally  as  a  soporific  (sleep  producer) — and  from 
2j  to  10  per  cent,  of  narcotine  (CMH,,NQ.).  Other  alka- 
loids associated  with  these  are  codeine  (C18H21NO3H2O), 
thebaine  (C19H21NO3),  papaverine  (C20H21NO4),  and 
narceine  (C23H27NO8,3H2O).  It  is  collected  chiefly  in 
Asia  Minor,  Turkey,  India,  and  Egypt. 

The  trade  before  the  Great  War  was  chiefly  in  the  hands 
of  Turkey,  the  Indian  opium  poppy  of  the  same  species 
having  a  smaller  morphine  content,  but  by  selection  and 
crossing  of  various  varieties,  it  is  hoped  to  produce  opium 
of  the  desired  qualities,  and  already  chemical  investigations 
have  disclosed  races  yielding  as  much  as  18  per  cent, 
morphine. 

Morphine  melts  at  254°  C.     1  all  of  which  are  white,  cry- 
Codeine         „          154*9°  C.  !-  stalline  bodies,  soluble  in 
Thebaine       „          193-0°  C.  J    water,  alcohol,  and  ether. 
Papaverine  melts  at  147-0°  C.,  is  insoluble  in  water,  but 
soluble  in  hot  alcohol  and  benzene. 

Narceine  is  soluble  in  alcohol,  but  hardly  soluble  in  water. 

Narcotine  melts  at  176°  C.,  is  a  white,  crystalline  body, 
insoluble  in  water,  but  soluble  in  chloroform  and  to  some 
extent  in  alcohol  and  ether. 


OPOPANAX—ORES  (TREATMENT  OF)  351 

OPOPANAX — A  resinous  gummy  substance  from  the  roots  of 
Pastinaca  opopanax  growing  in  warm  climates.  The  dried 
juice  from  Turkey  and  the  East  Indies  is  brought  in  lumps 
which  have  a  peculiar  odour  and  a  bitter  acrid  taste.  It  is 
used  in  perfumery. 

OPTOPHONE— See  Selenium. 

ORANGE  OIL— From  the  peel  of  the  fresh  fruit— the  sweet  oil 
from  Citrus  aurantium  and  the  bitter  oil  from  C.  bigaradia. 
Both  are  used  for  flavouring  purposes.  The  sweet  oil 
exhibits  a  sp.  gr.  of  from  0*847  to  0*851  ;  optical  rotation, 
+  97°  to  100°;  and  refractive  index,  i'47io  to  1*4742. 
The  bitter  oil  f  sp.  gr.,  0-852  to  0-856 ;  optical  rotation, 
+  90°  to  94° ;  and  refractive  index,  1*4730  to  1*4770. 

ORANGE-FLOWER  OIL  (Neroli  Oil)  has  a  sp.  gr.  of  0-87  to 
0-88  and  an  optical  rotation  of  +0°  to  5°. 

ORANGITE— See  Thorium. 

ORCHIL— A  dye  prepared  from  certain  lichens  by  treatment 
with  a  solution  of  potash  or  milk  of  lime,  from  which 
extracts  the  "  colouring  acids "  are  precipitated  by  the 
action  of  hydrochloric  or  acetic  acid.  "  French  purple  "  is 
an  orchil  dye.  (See  Archil.) 

ORES — Compounds  of  metals  as  found  in  nature,  derived 
from  the  outer  crust  of  the  earth,  and  concentrated  by 
natural  processes. 

ORES  (TREATMENT  OF) — The  treatment  of  ores  with  the  view 
of  separating  their  various  metallic  or  other  constituents 
necessarily  varies  according  to  their  nature,  and  many  of 
the  processes  are  described  under  the  headings  of  the 
metallic  elements  (see  Lead,  for  example)  ;  but  a  method  of 
separation  now  largely  used,  particularly  in  respect  of  the 
lead  and  zinc  sulphides,  is  that  known  as  "  flotation,"  in 
which  various  liquids,  such  as  amyl  alcohol,  creosote  oils, 
eucalyptus  oil,  pine  spirit,  and  turpentine,  are  employed,  while 
in  the  case  of  copper  ores  petroleum  products  are  favoured. 

The  powdered  ore  is  mixed  with  water  in  the  proportion 
of  about  i  ton  to  4  or  5  tons,  and  there  is  then  added 
from  £  to  2  Ib.  of  the  "flotation"  oil  so  as  to  produce 
frothing  when  air  is  blown  through  the  mixture,  with  the 
result  that  the  sulphide  ore  concentrates  in  the  froth,  while 
the  heavier  quartz  and  other  impurities  sink  to  the  bottom 
of  the  tank  or  remain  in  slight  suspension  in  the  water. 
Sometimes  an  oxidizing  agent  is  also  added. 

The  important  factors  are  agitation,  solubility  or  mis- 


352 


ORES— ORGANIC  ANALYSES 


ORES  (TREATMENT  OF)— 

cibility  of  the  flotation  liquid  (usually  oil),  the  surface 
tension,  and  the  size  of  the  ore  particles,  these  factors 
being  interdependent,  as  the  [more  the  oil  goes  into  solu- 
tion, the  more  the  bubbles  are  diminished. 

The  selective  agency  by  means  of  which  the  flotation 
method  separates  substances  like  galena  from  its  associated 
quartz  and  calcite  is  said  to  be  in  the  main  dependent  on 
the  contact  angle  formed  by  the  oiled  surfaces. 

The  froth  may  be  broken  up  by  spraying  wich  water, 
but  usually  the  concentrates  are  passed  direct  into  a 
pressure  filter,  thus  collecting  the  solid  separated  ore  for 
such  further  treatment  or  refinement  as  may  be  expedient. 

The  froth-flotation  process  has  also  been  applied  to  the 
purification  of  coal  by  the  elimination  of  shale  and  other 
waste  material  with  which  it  may  be  associated.  (See  p.  125. ) 

The  world's  production  of  the  more  important  metals 
(obtained  largely  from  sulphide  ores)  in  1913,  has  been 
reported  as  follows:  Copper,  1,006,000  tons;  lead,  1,187,000 
tons  ;  spelter,  998,000  tons  ;  and  tin,  129,000  tons;  and  it 
is  computed  that  to  produce  these  quantities,  approximately 
20,000,000  tons  of  ores  had  to  be  dealt  with,  chiefly  by 
roasting  them  or  their  concentrates. 

ORGANIC  ANALYSES  —  The  percentic  amounts  of  carbon 
and  hydrogen  contained  in  organic  substances  are  deter- 
mined for  the  most  part  by  a  process  of  combustion,  and, 
taking  sugar  by  way  of  example,  the  method  may  be 
described  as  follows :  A  definite  weight  is  taken  and,  after 
admixture  with  oxide  of  copper  (so  as  to  moderate  the 


Combustion  Furnace  as  in  Use. 

action  of  the  oxygen  gas,  as  referred  to  later),  placed  in  a 
little  vessel  or  boat  small  enough  to  be  pushed  into  a  length 
of  glass  combustion  tubing.  The  tube  containing  the  boat 
is  then  placed  in  a  so-called  combustion  furnace  (as  shown 
in  figure),  suitably  equipped  and  connected  with,  first  of  all, 


ORGANIC  ANALYSES  353 

ORGANIC  ANALYSES  (Continued)— 

a  drying-tube  of  previously  ascertained  weight,  and  then 
with  so-called  potash  bulbs  charged  with  a  solution  of 
potassium  hydroxide  of  sp.  gr.  1-26,  also  of  previously 
ascertained  weight. 

This  so-called  "  combustion  furnace "  is  extensively 
employed  for  exposing  solid  substances  up  to  a  red  heat 
(but  below  that  of  the  melting-point  of  the  combustion- 
tube  that  is  employed)  to  a  current  of  air,  oxygen,  or 
other  gas,  in  order  to  study  the  effects  produced,  by 
subsequent  examination  of  the  gaseous  and  residual 
products,  and  still  more  often  for  the  analytical  determina- 
tion of  the  constituents  of  organic  substances.  It  consists 
of  a  great  number  of  Bunsen  burners  set  in  a  row,  and  all 
rising  up  from  a  larger  gas-supply  pipe  below,  with  which 
they  are  connected.  They  sometimes  terminate  in  and  are 
surrounded  by  hollow  perforated  cones  or  blocks  of  earthen- 
ware, as  shown  by  d  in  illustration,  which  has  the  effect  of 
breaking  up  the  rlame  and  bringing  the  entire  mass  to  a 
glowing  red  heat  when  in  use.  The  framework  is  of  iron, 
and  so  constructed  that  when  the  furnace  is  in  use,  the  heat 
can  be  more  or  less  concentrated  on  the  combustion-tube 
by  means  of  earthenware  tiles  arranged  at  the  sides,  and 
which  can  also  be  placed  over  the  top  of  the  channel 
(running  along  and  over  the  tops  of  the  burners  below) 
in  which  the  combustion-tube  rests. 

Reverting  now  to  the  analysis  of  sugar,  a  current  of 
dried  oxygen  gas  is  passed  through  the  combustion-tube, 
while  gradually  heated  to  redness  in  the  furnace.  This 
causes  the  decomposition  of  the  sugar,  which  consists 
of  carbon,  hydrogen,  and  oxygen  (C12H22O1]L),  with  the 
result  that  the  carbon  is  burned  off  as  carbon  dioxide 
(CO2)  and  the  hydrogen  as  water  (H2O).  The  water  is 
absorbed  by  the  sulphuric  acid  or  calcium  chloride  con- 
tained in  the  drying-tube  (A)  and  the  carbon  dioxide  is 
absorbed  by  the  potash  in  the  bulbs  (B) ;  and  these  being 
severally  weighed  after  the  combustion  is  completed,  it  is 
known  that  the  increases  in  weight  of  the  two  appliances 
are  due  to  these  absorbed  products,  and  knowing  how 
much  carbon  and  hydrogen  are  severally  contained  in 
given  quantities  of  carbon  dioxide  and  water,  it  is  easy  to 
calculate  the  quantities  therefrom.  These  will  be  found 
to  make  up  so  much  of  the  weight  of  the  sugar,  and  the 
other  part  necessarily  consists  of  oxygen,  which  is  the  only 
other  constituent  of  the  sugar,  and  which  it  is  therefore 
unnecessary  to  specifically  determine  otherwise. 

23 


354  ORGANIC  ANALYSES-ORPIMENT 

ORGANIC  ANALYSES  (Continued) - 

To  determine  the  nitrogen  content  of  organic  substances 
the  combustion  is,  in  the  main,  conducted  as  already  de- 
scribed, but  a  current  of  carbon  dioxide  is  first  of  all  used 
to  clear  out  the  air  from  the  combustion  apparatus,  and 
afterwards  to  sweep  out  any  remaining  nitrogen  gas,  which 
is  collected  by  displacement  in  an  inverted  tube  of  mercury 
standing  in  a  dish  of  potassium  hydrate,  and  measured 
(making  due  corrections  for  temperature  and  pressure),  and 
from  this  measurement  its  weight  is  calculated. 

Any  oxygen  that  may  be  admixed  with  the  nitrogen  gas 
is  first  of  all  absorbed  by  introducing  an  alkaline  solution 
of  pyrogallic  acid.  (See  Pyrogallic  Acid.) 

In  other  cases,  instead  of  using  cupric  oxide,  fused  lead 
chromate  reduced  to  powder  is  employed,  and  there  are 
well-understood  methods  of  determining  the  percentages 
of  any  other  constituents,  such  as  sulphur  or  phosphorus. 
(See  also  Drying-Tube  and  Potash  Bulbs.) 

ORGANIC  BASES— See  Bases. 
ORGANIC  MATTER— See  Carbon. 

ORGANIZED — Arranged  in  definite  form  or  structure,  such  as 
cells,  fibres,  membranes,  hair,  skin,  etc. 

ORGANO-METALLIC  COMPOUNDS -Comprise  a  numerous 
class  of  colourless,  mobile,  liquid  substances  of  volatile 
character  in  which  organic  radicals,  such  as  the  alkyl 
groups,  are  combined  with  metals  ;  for  example,  zinc  methyl 
(Zn(CH3)2),  zinc  ethyl  (Zn(C2H5)2),  aluminium  methyl 
(A1(CH3)3),  and  lead  tetra-methyl  (Pb(CH3)4).  They  cor- 
respond to  the  chlorides  from  which  they  are  derived,  are 
decomposed  by  water,  and  burn  explosively  in  the  air. 

In  addition,  mercury,  tin,  and  some  other  metals  yield 
phenyl  derivatives — mercury  phenyl  (Hg(C6H5)2),  for 
example,  which  is  obtained  by  the  action  of  sodium 
amalgam  on  bromobenzene. 

By  oxidation,  zinc  ethyl  yields  zinc  ethylate 
(Zn(C2H5O)2),  and  this  by  further  oxidation  gives  zinc 
acetate  (Zn(C2H3O2)2). 

ORIGANUM  OIL— A  variety  of  thyme  oil  from  Trieste,  Cyprus, 
and  Smyrna  ;  sp.  gr.,  0-915  to  0*98  ;  rotation,  o°  to  —  13°. 
(See  Thymol.) 

ORMOLU  k  (Mosaic  Gold) — A  variety  of  brass  containing  more 
copper  and  less  zinc  than  ordinary  brass,  resembling  gold 
in  appearance. 

ORPIMENT—  See  Arsenic  Compounds. 


ORRIS  OIL— OSMOSIS  355 

ORRIS  OIL— A  yellowish,  semisolid,  fatty  substance  distilled 
from  the  rhizome  of  Iris  Florentina,  containing  myristic  acid, 
oleic  acid,  and  some  esters.  It  melts  at  44°  to  50°  C.,  is 
soluble  in  alcohol  and  ether,  and  is  used  in  making  perfumes 
and  cosmetics.  Irone,  a  methyl  ketone  (C13H20O),  is  the 
odoriferous  principle  of  the  iris  root,  and  probably  that  of 
the  violet  also.  Irone  is,  in  fact,  the  basic  source  of  several 
compounds  used  for  the  manufacture  of  violet  essence. 
(See  also  lonone.) 

ORTHITE — See  Lanthanum. 

ORTHOCLASE — A  kind  of  felspar  —  potassium  aluminium 
silicate. 

ORTHO-COMPOUNDS  are  substitution  products  derived  from 
benzene,  in  which  the  substituting  radicals  or  groups  are 
constitutionally  situate  in  certain  definite  positions  in  the 
nucleus — ortho-cresol,  for  instance. 

ORTHO-CRESOL— See  Cresol. 

OSAGE  ORANGE — A  material  obtained  from  the  bark  of 
the  osage  orange  tree,  indigenous  in  the  United  States, 
containing  some  25  per  cent,  tannin,  and  used  also  as  a  dye. 

OSMIUM  (Os) — Atomic  weight,  191  ;  sp.  gr.,  22-47;  melting- 
point,  2,700°  C.  A  rare  element  of  the  platinum  group,  and 
the  most  refractory;  found  in  alloyed  association  with 
iridium  in  certain  platinum  ores,  and  notably  in  so-called 
osmiridium,  in  parts  of  which  the  osmium  content  runs  as 
high  as  from  30  to  40  per  cent.  It  is  a  hard,  bluish- white, 
and  the  heaviest  known  metal,  possessing  catalytic  pro- 
perties. It  can  be  prepared  from  its  oxides  by  reduction ; 
is  known  in  crystalline  and  amorphous  forms,  and  burns 
brightly  when  strongly  heated,  forming  osmium  tetroxide. 
The  amorphous  variety  is  dissolved  by  aqua  regia  and  the 
tetroxide  is  thus  produced,  but  the  compact  form  is  insoluble 
in  all  acids.  Four  oxides  are  known — viz.,  OsO,  Os2O3, 
OsO2,  and  OsO4 — and  there  are  salts  corresponding  to  the 
sesquioxide.  Three  chlorides  are  known — OsCl2,  OsCl3, 
and  OsCl4. 

OSMOSIS — The  mixing  of  two  liquids  separated  by  a  porous 
diaphragm  ;  for  instance,  if  a  bladder  containing  alcohol  be 
placed  in  a  basin  of  water,  some  of  the  spirit  will  pass 
through  the  diaphragm  into  the  water,  and  some  of  the 
water  will  pass  through  it  into  the  alcohol.  In  most  cases 
the  quantities  of  the  two  different  liquids  travelling  in 
opposite  directions  are  unequal. 


356  OSMOSIS— OXALATES 

OSMOSIS  (Continued)— 

If  a  porous  earthenware  vessel  be  substituted  for  the 
animal  membrane  and  the  pores  thereof  covered  by  the 
deposition  thereon  of  a  finely  divided  precipitate  such  as 
copper  ferrocyanide  (thus  producing  a  semipermeable 
surface),  it  is  found  that,  using  a  solution  of  sugar,  water 
will  pass  therefrom  through  the  surface,  but  the  sugar  dis- 
solved therein  will  not  permeate.  If,  therefore,  a  cell  of 
unglazed  porcelain  be  prepared  coated  internally  in  this 
way,  charged  with  a  solution  of  sugar  and  then  immersed 
in  water,  the  liquid  will  rise  within  the  cell  or  tube  to  a 
certain  extent  above  the  level  of  the  surrounding  water,  by 
reason  of  the  passage  of  the  water  through  the  cell,  no 
sugar  passing  out ;  but  when  a  certain  pressure  is  reached, 
equilibrium  is  established,  and  water  then  passes  in  each 
direction  at  equal  rates ;  so  that  by  connecting  such  an 
appliance  with  a  manometer  the  pressure  reached  can  be 
measured  and  recorded  as  the  "  osmotic  pressure." 

Expressed  otherwise,  osmosis  represents  the  increase  in 
the  volume  of  the  dialyzing  fluid  in  the  interior  of  the  cell, 
and  this  phenomenon  is  always  observed  whenever  a 
so-called  dispersoid  is  brought  in  contact  with  a  less  con- 
centrated one.  At  the  same  temperature  and  strength  of 
solution,  different  substances  exhibit  different  pressures,  and 
it  has  thus  been  found  that  the  analogy  between  the  laws 
governing  these  phenomena  and  those  relating  to  gaseous 
pressure  is  close,  and  that  osmotic  pressure  increases  with 
rise  and  diminishes  with  fall  of  temperature. 

The  term  u  dispersoids  "  as  here  used,  means  heterogeneous 
combinations  of  Graham's  "  sols  "  and  "  gels."  "  Isotonic 
solutions  "  are  solutions  of  equal  osmotic  pressure,  and  true 
solutions  give  osmotic  pressures  in  proportion  to  their 
molecular  weights.  (See  Dialysis.) 

OSSEIN — A  variety  of  gelatin  or  albuminous  substance  present 
in  and  prepared  from  bones.  (See  Gelatin.) 

OSTEOLITE — A  mineral  calcium  phosphate  (Ca3(PO4)2,2H2O). 

OTOBA  BUTTER — The  fat  expressed  from  the  fruit  of  My- 
ristica  otoba,  containing  glycerides  and  some  sesquiterpenes ; 
saponifkation  value,  185;  and  melting-point,  34°  C. 

OTTO  OF  ROSES— See  Attar  of  Roses. 

OXALATES — Compounds  of  oxalic  acid  with  metals  and  bases. 
The  alkaline  oxalates  are  soluble  in  water,  but  the  others 
are  for  the  most  part  insoluble. 


OXALIC  ACID— OXIDATION  357 

OXALIC  ACID  (C2H2O4,2H2O)  may  be  regarded  as  an  oxi- 
dation product  of  the  alcohol  named  ethylene  glycol 
(C2H6O2),  and  is  dibasic.  It  occurs  in  nature  combined 
with  potassium  as  oxalate  (K2C2O4)  in  many  plants,  par- 
ticularly in  wood- sorrel  (Oxalis  acetosella)  and  varieties  of 
Rumex  ;  in  the  free  state  in  some  varieties  of  Boletus,  and 
as  calcium  oxalate  in  rhubarb  root  and  many  lichens. 
Urinary  deposits  and  calculi  also  often  contain  the  calcium 
salt.  It  can  be  made  by  the  action  of  nitric  acid  upon 
sugar,  but  is  prepared  commercially  by  fusing  a  mixture  of 
cellulose  (sawdust),  with  potassium  and  sodium  hydroxides 
at  from  200°  to  220°  C.  in  flat  iron  vessels.  The  fused 
mass  is  afterwards  extracted  with  water,  and  upon  addition 
of  calcium  chloride,  insoluble  calcium  oxalate  (CaC2O4)  is 
precipitated,  and  from  this  compound,  oxalic  acid  is  obtained 
by  treatment  with  sulphuric  acid.  The  soft  woods  give 
a  better  yield  of  oxalic  acid  than  the  hard  woods. 

It  can  similarly  be  obtained  from  sugar  and  starch. 

Oxalic  acid  can  also  be  prepared  by  heating  sodium  car- 
bonate with  carbon  dioxide  under  pressure,  thus  producing 
sodium  formate  (NaCHO2),  and  when  this  is  heated  with 
sodium  carbonate,  oxalate  of  sodium  is  produced.  By 
adding  a  calcium  salt  to  the  solution  of  sodium  oxalate, 
calcium  oxalate  is  precipitated,  and  when  that  compound 
is  treated  with  sulphuric  acid,  the  oxalic  acid  is  set 
free. 

Oxalic  acid  is  very  poisonous,  crystallizes  in  large  trans- 
parent prisms,  which  slowly  effloresce  in  the  air,  and  is  very 
soluble  in  water  and  to  some  extent  in  alcohol.  The  hydrated 
acid  melts  at  98°  C.  in  its  water  of  crystallization,  while  at 
100°  C.  it  becomes  anhydrous,  and  at  110°  to  120°  C.  it 
decomposes  and  yields  a  mixture  of  carbon  monoxide  and 
dioxide. 

Oxalic  acid  is  used  in  the  dyestuffs  and  textile  industries, 
and  for  various  other  applications.  The  ferrous-potassic 
oxalate  (FeK2(C2O4)2)  is  a  powerful  reducing  agent,  and  is 
used  in  photography  as  "  oxalate  developer." 

OXAMIDE  (C2H4N2O2or  NH2.CO.CO.NH2)— A  white  crystal- 
line substance,  being  the  normal  amide  of  oxalic  acid. 

OXIDASES — Enzymes  capable  of  effecting  oxidation  as  distinct 
from  the  hydrolytic  action  of  most  enzymes. 

OXIDATION  is  a  process  by  means  of  which,  oxygen  is  either 
added  to  a  substance  (as  in  the  simple  case  of  converting 
mercury  into  its  red  oxide  by  heating  it  in  air  or  oxygen) 


358  OXIDATION—  OXYGEN 

OXIDATION  (Continued)— 

or  made  to  remove  hydrogen  from  a  substance  as  in  the 
case  of  oxidizing  ethyl  alcohol  into  aldehyde  — 

C2H60  +  O  =  C2H40  +  H20. 

When  the  process  is  carried  still  further,  oxygen  is  also 
added,  acetic  acid  being  produced  — 

C2H6O  +  02  =  C2H402  +  H20. 

Combustion  of  organic  matters  and  the  roasting  of  metallic 
sulphides  are  also  acts  of  oxidation.  (See  Oxidizing 
Agents.) 

OXIDES  —  See  Bases,  Chemical  Compounds,  p.  101,  and  Oxygen. 

OXIDIZING  AGENTS—  Chemical  substances  which  are  capable 
of  giving  up  oxygen  to  other  substances  having  an  affinity 
for  it,  including  air,  oxygen,  ozone,  and  many  substances 
rich  in  oxygen,  as,  for  example,  potassium  permanganate 
(KMnO4),  potassium  dichromate  (K2Cr2O7),  chromic 
anhydride  (CrO3),  nitric  acid  (HNO3),  and  the  various  per- 
oxides. For  instance,  gaseous  ammonia  is  oxidized  by 
chromic  anhydride,  which  substance  is  reduced  thereby  to 
sesquioxide  as  shown  in  the  equation  — 


(See  also  Oxidation.) 

OXIMES  —  A  series  of  bodies  obtained  from  aldehydes  and 
ketones  by  condensation  of  the  carbonyl  group  (C:O)  with 
the  compound  hydroxylamine  (NH2.OH). 

OXYDASES—  See  Oxidases. 

OXYGEN    (O)    (and   its    Compounds)    and    OZONE  —  Oxygen 

(atomic  weight,  16;  melting-point,  -218°  C.)  was  origin- 
ally obtained  by  heating  the  red  oxide  of  mercury  in  the 
concentrated  rays  of  the  sun  through  the  medium  of  a 
powerful  lens.  Associated  in  combination  with  hydrogen, 
it  exists  in  water  (of  which  it  makes  up  eight-ninths  of 
its  weight),  and  it  has  been  roughly  estimated  to  form 
nearly  one-half  by  weight  of  the  various  rocks  of  which  the 
earth's  crust  is  composed. 

Oxygen  gas  is  not  only  yielded  by  electrolysis  of  water 
and  by  heating  the  red  oxide  of  mercury  — 

HgO  =  Hg  +  0, 

but  a  number  of  so-called  peroxides,  of  which  manganese 
dioxide  is  typical,  yield  to  the  same  heat  treatment,  thus  : 

3MnO2=Mn3O4 


OXYGEN  AND  OZONE  359 

OXYGEN  (Continued)— 

That  is  to  say,  the  manganese  dioxide  gives  off  oxygen  gas, 
and  is  reduced  to  a  lower  state  of  oxidation  when  heated  to 
redness. 

Barium  peroxide  (BaO2)  behaves  similarly  : 

BaO2=BaO-i-O. 

This  change  takes  place  at  a  temperature  of  1,400°  C., 
and  when  completed,  the  BaO  can  be  reconverted  to  BaO2 
by  exposing  it  to  a  current  of  air  under  pressure  at  the  lower 
temperature  of  700°  C.  It  is  upon  the  basis  of  these  two 
alternate  changes  that  Brin's  method  of  manufacturing 
oxygen  is  based. 

Potassium  chlorate  (KC1O3)  when  heated  to  a  state  of 
fusion  also  gives  off  oxygen,  being  reduced  to  the  chloride 
(KCl). 

Pure  oxygen  gas  is  colourless,  tasteless,  and  slightly 
soluble  in  water  (i  volume  of  which  at  o°  C.  dissolves 
0-0489  volume  of  the  gas),  fish  being  dependent  upon  this 
dissolved  quantity  for  respiration.  In  fact,  oxygen  is  the 
only  gas  that  is  capable  of  supporting  respiration. 

The  oxygen  of  the  air,  of  which  it  constitutes  about  one- 
fifth,  can  be  separated  from  the  associated  nitrogen  by 
chemical  means,  and  it  has  been  found  possible  to  reduce 
the  air  to  a  fluid  or  water-like  state.  This  is  done  by 
pumping  the  air  at  a  very  low  temperature  and  under  great 
pressure  into  vessels  made  exceedingly  cold.  From 
liquefied  air,  the  two  gases,  nitrogen  and  oxygen,  pass  again 
into  the  state  of  vapour  at  different  temperatures ;  so  that 
it  is  possible  to  boil  off  the  nitrogen — or  most  of  it — before 
the  oxygen,  and  this  process  is  used  for  the  manufacture 
of  liquid  oxygen  on  a  large  scale. 

Liquid  air  is  so  cold  that  when  such  materials  as  flesh  or 
india-rubber  are  cooled  in  it,  they  become  brittle  and  when 
struck  with  an  hammer  fly  into  pieces  like  glass. 

Oxygen  is  still  liquid  at  —210°,  and  in  this  form  is  of  a 
pale  steel-blue  shade  of  colour  and  exhibits  strong  mag- 
netic properties. 

Pure  oxygen  is  now  an  article  of  commerce,  and  is  not 
only  largely  used  for  the  treatment  of  certain  complaints  by 
inhalation  but  also  for  many  manufacturing  and  trade 
purposes,  including  its  employment  in  association  with 
hydrogen  or  acetylene  for  the  production  of  flames  used  for 
the  cutting  and  welding  of  metals. 

Among  other  applications  of  liquid  oxygen  is  that  of  its 
use  as  an  explosive  when  mixed  with  combustible  matter, 


360  OXYGEN  AND  OZONE 

OXYGEN  (Continued)— 

such  as  sawdust  or  carbon.  Liquefied  oxygen  in  itself  is 
not  explosive,  but  cartridges  of  paper  filled  with  sawdust 
or  other  combustible  and  soaked  in  the  liquid  oxygen  for 
some  five  or  ten  minutes  and  lighted  in  a  closed  space,  such 
as  a  borehole  made  for  blasting  purposes,  are  highly  ex- 
plosive. A  litre  of  oxygen  used  in  this  way  is  said  to  be 
the  equivalent  of  i  kg.  of  black  gunpowder  and  very  much 
cheaper. 

The  importance  of  oxygen  in  respect  of  respiration  and 
combustion  is  referred  to  elsewhere.  (See  Air.) 

Oxygen  exhibits  powerful  and  widely  spread  affinities  for 
other  substances,  forming  various  oxides  with  a  great 
number  of  elements,  combining  with  hydrogen  to  form 
water  and  hydrogen  dioxide,  and  entering  into  the  com- 
position of  an  infinite  number  of  chemical  compounds. 

Ozone. — When  oxygen  gas  is  subjected  to  the  influence  of 
the  silent  electric  discharge,  it  is  converted  into  what  is  called 
an  allotropic  state  and  becomes  ozone  ;  the  chemical  differ- 
ence being  that  whereas  the  molecule  of  oxygen  contains 
2  atoms  (O2),  that  of  ozone  contains  3  atoms  (O3) ;  and  the 
properties  of  the  two  substances  are  perfectly  distinct. 
Ozone  is  also  produced  when  phosphorus  is  partially  im- 
mersed in  water  and  exposed  to  the  air  :  ozone  is  formed  in 
the  air  and  hydrogen  peroxide  (H2O2)  is  formed  in  the  water. 
As  prepared  by  the  use  of  electrical  "  ozonators  "  it  is  used 
commercially  for  the  bleaching  of  wax,  textiles  and  other 
fabrics,  paper  pulp,  sponges,  and  for  giving  drying  proper- 
ties to  oils,  varnishes,  and  paints. 

Oxygen  is  quite  tasteless  and  odourless,  whilst  ozone  has 
a  peculiar  fishy  odour,  is  soluble  in  turpentine,  and  exhibits 
very  superior  powers  as  an  oxidizing  and  bleaching  agent. 
For  example,  silver  does  not  suffer  oxidation  when  exposed 
to  pure  oxygen,  but  it  is  rapidly  attacked  by  ozone  and  be- 
comes peroxidized.  It  has  also  the  power  of  decomposing 
potassium  iodide,  setting  iodine  free.  By  way  of  absolute 
proof  that  ozone  and  oxygen  are  identical  in  matter,  it  may 
be  stated  that  they  are  mutually  convertible,  ozone  being 
retransformed  into  oxygen  by  raising  it  to  a  temperature 
of  246°  C. — 2  volumes  of  ozone  thus  yielding  3  volumes  of 
oxygen. 

Ozone  is  often  found  present  in  small  quantity  in  the  air, 
and  there  is  evidence  of  its  presence  in  the  upper  atmo- 
sphere at  high  altitudes  ;  doubtless,  it  is  formed  in  lightning 
discharges  when  the  oxygen  of  the  air  is  subjected  to 
electrical  influences.  In  the  liquefied  condition,  ozone 
exhibits  an  intense  blue  colour  and  is  extremely  explosive. 


OXYGENATED  WATER— PAINTS  361 

OXYGENATED  WATER— Water  mechanically  charged  with 
oxygen  gas  and  not  to  be  confounded  with  hydrogen 
dioxide. 

OXYILEMOGLOBIN — The  compound  formed  in  the  blood  by 
the  action  of  inspired  oxygen  on  its  haemoglobin  constituent, 
which  carries  oxygen  to  the  animal  tissues. 

OXYHYDROGEN  FLAME  —  Produced  by  burning  a  mixture 
of  oxygen  and  hydrogen  gases  ;  until  superseded  by  the 
electric  furnace  it  was  used,  amongst  other  purposes,  for 
the  manufacture  of  artificial  rubies  and  sapphires.  Its 
temperature  is  in  the  neighbourhood  of  2,800°  C. 

OZOKERITE — A  mineral  wax  of  yellowish-black  or  green 
colour  occurring  in  the  vicinity  of  coal  in  Galicia,  Moldavia, 
Utah,  Wyoming,  and  elsewhere.  It  is  in  the  nature  of  a 
paraffin  hydrocarbon  and  is  used  in  connection  with  the 
manufacture  of  candles,  sealing-wax,  paints,  and  other 
articles.  Its  sp.  gr.  is  0-85  to  0-95  ;  it  melts  between  55° 
and  110°  C.,  according  to  variety,  and  is  soluble  in  benzol, 
turpentine,  carbon  disulphide,  etc. 

By  purification  and  bleaching  it  gives  the  ceresine  of 
commerce. 

OZONE— See  Oxygen,  p.  360. 

PAINTS — Mixtures  of  white-lead,  red-lead,  zinc  oxide,  zinc 
sulphide,  lime,  barium  sulphate,  or  other  mineral  bases  with 
boiled  linseed  oil  and  turpentine,  used  to  prevent  the  rust- 
ing of  iron  and  for  the  preservation  of  wood  and  other 
surfaces ;  also  for  artistic  and  decorative  purposes.  Tests 
have  definitely  proved  that  a  paint  made  with  50  per  cent, 
barytes  and  50  per  cent,  white-lead  is  more  durable  as  a 
pigment  than  pure  white-lead  paint. 

A  luminous  paint  of  soft  greenish  glow  and  great  dura- 
bility is  now  prepared  by  incorporating  a  small  proportion 
of  radium  salt  in  a  zinc  sulphide  base,  using  some  good 
binding  material  such  as  nitro-cellulose  lacquer. 

Volatile  liquids,  such  as  benzene,  petrol,  turpentine, 
naphtha,  and  acetone,  are  used  in  paint-making  as  thinners 
or  vehicles,  and  upon  evaporation,  leave  the  boiled  linseed 
oil  and  mineral  base  on  the  coated  surfaces.  The  linseed 
oil  absorbs  oxygen  from  the  air,  and  mixed  with  the  base 
forms  a  conglomerate  solid  mass  constituting  the  real  paint. 
Turpentine  differs  from  the  other  vehicles  named,  inasmuch 
as  it  does  not  volatilize  so  quickly,  and  absorbing  oxygen 
from  the  air J  (particularly  in  warm  weather  and  sunlight), 
forms  a  skin  of  oxidized  product,  thus  adding  slightly  to 
the  weight  of  the  dry  paint.  (See  also  Enamel  Paints, 
Lithopone,  and  Varnishes.) 


362  PALLADIUM— PALM  OIL 

PALLADIUM  (Pd) — Atomic  weight,  106-7;  SP-  gr->  II'5J 
melting-point,  about  1,500°  to  1,550°  C.  Palladium  is  a 
rare  metal  of  the  platinum  group  of  elements,  and  is  found 
associated  in  platinum  ores  to  the  extent  of  from  J  to 
i  per  cent. 

It  is  white,  fairly  ductile  and  malleable,  and  is  especially 
interesting  on  account  of  its  capability,  particularly  in  the 
spongy  condition,  of  "occluding"  gases.  If,  for  example, 
a  wire  of  palladium  be  made  the  negative  pole  of  a  Voltaic 
cell,  it  will  in  course  of  the  decomposition  of  water,  absorb 
as  much  as  936  times  its  own  volume  of  hydrogen  gas, 
during  which  time  it  increases  very  largely  in  bulk.  A 
piece  of  foil  of  the  metal  will,  when  heated  to  between  90° 
and  97°  C.  in  an  atmosphere  of  hydrogen,  absorb  as  much 
as  643  times  its  own  volume  of  that  gas. 

Palladium  is  readily  soluble  in  hot  nitric  acid,  and  its 
compounds,  which  resemble  those  of  platinum  in  form  and 
general  characters,  include  three  oxides  (Pd2O,  PdO,  and 
PdO2),  and  two  chlorides  (PdCl2  and  PdCl4),  which  are 
soluble  in  water,  etc. 

The  metal  can  be  obtained  by  ignition  of  the  double 
palladium-ammonium  chloride,  and  is  used  as  an  alloy  with 
gold,  silver,  or  copper  in  dentistry,  also  for  balance  wheels 
of  watches  and  as  a  catalyst,  etc.  (See  Occlusion.) 

PALM  OIL  (Palm  Butter)  is  obtained  by  crushing  the 
fermented  fruit  of  the  West  African  oil  palm  Rlceh  guineensis 
and  other  species,  including  Cocos  butymcea  and  A  voira  elais, 
while  the  South  American  oil  comes  from  the  analogous 
but  smaller  Elais  melanococca.  It  consists  of  the  glycerides  of 
palmitic,  stearic,  and  oleic  acids  with  a  large  proportion  of 
free  palmitic  acid,  varying,  it  is  stated,  from  12  per  cent,  in 
the  fresh  to  over  50  per  cent,  in  old  oil.  It  is  purified  by 
melting  to  remove  water,  and  can  be  decolourized  by 
chemical  agencies.  The  sp.  gr.  of  the  West  African  supply 
is  generally  given  as  o '92  to  0*93  and  the  iodine  value  as  13*5, 
but  a  recent  publication  gives  the  following  constants  of  the 
two  supplies  above  referred  to : 


West  African. 


South  American 
Noli  Palm  Oil. 


Sp.gr.            0-8586  0-8636 

Solidification  point    ...  36°-46°  33-6° 

Saponification  value ...  196-205  199 

Iodine  value 53~57  83-5 

Palm  oil  is  of  orange-yellow  colour,  has  the  consistence 
of  butter,  and  is  extensively  used  in  making  margarine,  soap, 


PALM  OIL-PANCREATIC  JUICE  363 

PALM  OIL  (Continued)— 

and  candles,  also  in  admixture  with  tallow  and  some  pro- 
portion of  alkali  as  railway-wagon  grease. 

The  flesh  of  the  South  American  fruit  contains  29  per 
cent,  of  oil,  equal  to  31-5  per  cent,  in  the  desiccated  fruit. 

Palm  Nut  or  Kernel  Oil  is  yellowish,  fat,  and  edible,  and 
is  obtained  by  crushing  the  kernels  or  extracting  the  oil 
therefrom  by  solvents.     It   consists   of   the  glycerides  of 
palmitic,    stearic,   myristic,    lauric,    caprylic,    and    caproic 
acids,  and  is  practically  devoid  of  free  fatty  acids.     It  is 
soluble  in  alcohol,  carbon  disulphide,  and  ether.     Its  sp.  gr. 
is  generally  given  as  0-952,  and  the  iodine  value  as  13-5,  but 
the  communication  above  referred  to  gives  the  constants  as 
follows : 

West  African.       Noli  Palm  Oil. 
Sp.  gr.         ...  ...          0-8731  0-8651 

Solidification  point    ...        2o°-25'5°  26*9° 

Saponification  value  ...         242-255  234 

Iodine  value  ...        10-3-17-5  27-7 

The  kernels  of  the  South  American  fruit  contain  45-4  per 
cent,  oil,  equal  to  48-7  per  cent,  in  the  desiccated  seeds. 
The  oil  is  used  in  soap-making,  chocolate  articles,  and  in 
pharmacy. 

Curua  Palm  Oil  (from  Attalea  spectabilis)  from  Brazil. 
The  dry  kernels  yield  65-3  per  cent,  of  semisolid, 
greenish  oil  of  sp.  gr.,  0-8693;  refractive  index,  1*447; 
melting-point,  23*6°  C.;  saponification  value,  259-5;  and 
iodine  value,  8*9. 

PALM  WAX — From  the  palm  named  Ceroxylin  andicola.  (See 
Waxes.) 

PALMAROSA  OIL— See  Geranium  Oil. 

PALMITIC  ACID  (Ci6H32O2)— A  constituent  of  most  of  the 
harder  fats,  including  spermaceti,  and  especially  palm  oils. 
It  is  tasteless,  odourless,  soluble  in  hot  alcohol  and  ether, 
and  is  obtained  in  crystals  which  melt  at  63-4°  C.  It  can 
be  distilled  at  reduced  pressure  without  change  and  when 
saponified  with  alkalies  forms  soaps.  (See  Fats.) 

PALMITIN— See  Fats. 

PANCREATIC  JUICE— A  secretion  of  alkaline  reaction,  con- 
taining ferments  (enzymes)  which  assist  in  completing  the 
digestion  of  substances  contained  in  the  chyme  and  in 
emulsifying  fatty  bodies  also  present  therein.  When 


364  PANCREATIC  JUICE— PARA-CRESOL 

PANCREATIC  JUICE  (Continued)— 

agitated  with  neutral  oils,  pancreatic  juice  makes  perfect 
emulsions.  This  emulsification  enables  the  fatty  matters 
to  pass  through  the  pores  of  the  mucous  membranes  into 
the  chyle  ducts.  In  common  with  saliva  it  also  has  the 
property  of  converting  starch  into  sugar.  (See  Enzymes.) 

PANCREATINE— See  Enzymes. 

"  PANDERMITE  "--A  trade  name  for  calcium  borate,  used  in 
compounding  ceramic  frits. 

PAPAIN — See  Enzymes. 
PAPAVERINE— See  Opium. 

PAPER  was  made  almost  exclusively  from  rags  down  to  1866, 
but  in  that  year  esparto  grass  was  first  employed,  and  since 
then,  wood  pulp  and  straw  have  been  very  extensively  used 
in  its  manufacture,  as  also  the  cellulose  made  from  the 
bamboo  and  Savannah  grasses.  To  prepare  wood  pulp,  the 
bark  is  removed  and  after  being  cut  up  into  small  pieces, 
the  wood  is  boiled  with  a  mixture  of  bisulphite  of  calcium 
(Ca(HSO3)2)  or  magnesia  and  water,  which  renders  the  non- 
cellulose  parts  soluble,  and  thus  yields  from  40  to  50  per  cent, 
of  pulp  consisting  practically  of  cellulose.  The  bleaching  of 
pulp  is  effected  by  means  of  sulphur  dioxide.  In  Germany, 
yarn  is  now  prepared  on  a  large  scale  from  paper. 

Many  qualities  of  paper  are  loaded  with  mineral  matters, 
such  as  china  clay  and  calcium  sulphate,  for  the  purpose  of 
filling  the  pores  and  giving  a  good  surface,  whilst  for 
writing-paper,  and  some  other  qualities,  sizing  is  resorted 
to  so  as  to  render  the  surface  impermeable  to  ink.  This  is 
effected  either  by  adding  resin  to  the  pulp  and  afterwards 
adding  alum  solution  so  as  to  fix  it  in  the  body  of  the 
paper,  or  the  spun  paper  is  passed  through  a  bath  of 
gelatin  solution  and  then  through  one  of  alum  solution  to 
precipitate  the  gelatin  in  the  pores  of  the  paper.  The 
paper  is  spun  by  streaming  the  pulp  mixture  over  a  wire 
cloth,  thus  forming  a  continuous  sheet,  which  is  afterwards 
pressed  between  hot  rollers,  thus  drying  and  at  the  same 
time  polishing  it.  (See  Cellulose  and  Silk,  Artificial.) 

PARA  -  COMPOUNDS  —  Substitution  products  derived  from 
benzene  in  which  the  substituting  radicals  or  groups  are 
constitutionally  placed  in  certain  definite  positions  in  the 
benzene  nucleus — para-cresol,  for  instance. 

PARA-COUMARONE  RESIN— See  Coumarone. 
PARA-CRESOL— See  Cresol. 


PARAFFIN  OIL—PEA-NUT  OIL  365 

PARAFFIN  OIL — A  general  name  given  to  a  number  of  oily 
liquids  heavier  than  kerosene,  in  the  nature  of  hydrocarbons 
of  flash-point  from  300°  to  450°  F.,  variously  derived  from 
the  distillation  of  wood,  coal,  lignite,  peat,  shale,  petro- 
leum, etc. 

There  are  varieties  of  yellowish,  brown,  red,  or  green 
colour,  used  for  lubricating  purposes  and  in  leather- 
dressing.  (See  Petroleum.) 

PARAFFINS — See  Hydrocarbons  and  Petroleum. 
PARAFFIN  WAX— See  Waxes. 

PARAFFINUM  LIQUIDUM,  B.P.— A  pharmaceutical  prepara- 
tion, being  a  mixture  of  hydrocarbons  of  the  methane  series, 
of  sp.  gr.  860  to  890,  with  a  boiling-point  above  360°  C. ; 
used  as  an  internal  lubricant,  also  as  a  vehicle  for  oily 
spray  solutions  containing  menthol,  thymol,  and  volatile 
oils. 

PARAFORM  or  PARAFORMALDEHYDE,  (CH,O)a,  is  a 
white  substance  soluble  in  hot  water,  constituting  a  poly- 
meric form  of  formaldehyde  (CH2O),  and  when  volatilized 
it  passes  back  again  into  that  form.  Its  disinfecting  power 
in  vaporous  form  is  identical  with  that  of  formaldehyde. 

PARALDEHYDE  or  PARA-ALDEHYDE  (C6H12O3)— A  water- 
white  liquid  of  pleasant  odour,  being  a  polymer  of  acetalde- 
hyde;  used  as  a  soporific.  Sp.  gr.,  0-9943;  and  boiling- 
point,  124°  C. 

PARIS  GREEN  (Schweinfurt  Green)— Copper  arseno-acetate 
(3CuOAs2O3.Cu(C2H3O2)2) ;  an  emerald  -  green  pigment 
prepared  by  boiling  basic  acetate  of  copper  with  arsenic 
trioxide. 

PASTEURIZATION — The  sterilization  of  milk  by  heating  to  a 
temperature  of  82°  C.  for  a  few  minutes. 

PATCHOULI  OIL' — Sp.  gr.,  0-970  to  0-995;  rotation,  -50° 
to  —  68°.  An  essential  oil  derived  from  the  leaves  of  the 
herb  Pogostemon  patchouli,  indigenous  in  Northern  India  and 
China,  and  grown  in  the  West  Indies  and  the  Straits  Settle- 
ments. It  is  yellowish  and  somewhat  thick,  soluble  in 
alcohol  and  ether,  and  used  in  perfumery.  Its  constituents 
include  eugenol  and  cinnamic  aldehyde. 

PEA-NUT  OIL— See  Arachis  Oil,  p.  36. 


366  PEARL  ASH— PEAT 

PEARL  ASH — An  American  crude  potassium  carbonate  pre- 
pared from  wood  ashes  by  concentrating  the  lixiviate,  until 
the  less  soluble  salts  have  crystallized  out,  then  evaporating 
the  mother-liquor  to  dryness  and  calcining  the  residue. 

PEARLS  are  secretions  of  certain  shell-fishes  such  as  the  pearl 
oyster,  and  consist  of  calcium  carbonate  interstratified  with 
certain  membranes  resulting  from  chemical  changes,  to  a 
contamination  of  which  the  occasional  loss  of  lustre  is 
probably  due.  The  chief  fisheries  are  in  the  Persian  Gulf 
and  Ceylon.  (See  Mother  of  Pearl.) 

PEAT — A  carbonaceous  deposit  occurring  in  fen  and  marshy 
areas,  resulting  from  chemical  changes  affecting  the  mossy 
and  other  plants  which  abound  therein,  often  found  in  beds 
of  from  some  inches  to  many  feet  in  thickness,  and  con- 
taining from  24  to  30  per  cent,  of  carbon.  When  air- 
dried,  it  forms  a  valuable  fuel,  and  when  coked  in  ovens  or 
distilled,  it  yields  many  valuable  products  allied  in  character 
to  those  derived  from  lignite  and  coal.  It  is  stated  that  by 
use  of  the  so-called  electro-osmose  filter,  85  parts  of  water 
can  be  easily  removed  from  hydraulically  mined  peat  con- 
taining only  5  parts  of  the  dry  substance  in  100  parts  of 
suspension,  so  that  where  water-power  is  available  to 
produce  electricity  sufficiently  cheap,  and  peat  beds  are 
near  enough  and  thick  enough,  this  process  of  drying  holds 
out  great  promise. 

The  average  calorific  value  for  Irish  air-dried  peat  is 
about  6,850  B.T.U.  per  lb.,  and  its  ash  content  is  3  per 
cent.  The  nitrogen  content  increases  from  the  surface 
(i  per  cent.)  downwards  (to  2*5  per  cent,  at  the  bottom  of 
deep  bogs),  and  it  is  calculated  that  it  should  yield  about 
100  Ibs.  of  ammonium  sulphate  per  ton  of  air-dried  peat. 
Its  main  uses,  however,  at  present  are  as  litter,  cattle  food, 
and  fuel,  the  last  named  including  the  various  distillation 
products.  It  also  has  value  by  reason  of  its  nitrogen 
content  as  a  fertilizer,  the  black  decomposed  qualities  being 
best  for  such  use. 

To  be  of  use  for  carbonization,  it  is  stated  that  peat  must 
not  contain  more  than  25  per  cent,  of  moisture  or  5  per 
cent,  ash,  and  it  then  yields  30  per  cent,  gas,  5  per  cent,  tar, 
and  0-25  per  cent,  ammonia  at  a  retort  temperature  of 

1,100°  C 

The  incomplete  combustion  of  peat  in  a  gas-producer 
yields  some  proportion  of  volatile  oils  and  wax,  resembling 
the  Montana  wax  of  lignite,  a  soft  pitch  being  left  behind. 
The  volatile  oils  contain  a  proportion  of  phenolic  bodies  of 


PEAT— PEPPERMINT  (OIL  OF)  367 

PEAT  (Continued)— 

an  acidic  character  allied  to  those  yielded  by  the  distillation 
of  blast  furnace  tar — that  is  to  say,  of  a  higher  germicidal 
character  than  ordinary  coal-tar  distillates.  The  calorific 
value  of  dry  turf  is  said  to  be  about  half  that  of  coal. 

Wet  peat  from  an  undrained  bog  contains  about  8  per 
cent,  dry  material  and  2- 8  per  cent,  charcoal,  while  a  well- 
drained  bog  gives  a  peat  of  which  100  tons  will  yield 
about  3' 5  tons  of  charcoal. 

It  has  been  estimated  that  in  Ireland,  the  peat  contained 
in  the  bogs  amounts  to  more  than  ten  times  the  proved  coal 
reserves  of  that  country. 

PECTOSE — The  pulpy  part  of  fleshy  unripe  fruits,  insoluble  in 
water,  and  which  becomes  converted  into  pectin  (which  is 
soluble)  by  the  agency  of  heat  or  by  the  ripening  process. 
It  is  this  last-named  substance  that  imparts  to  their  juices 
the  property  of  gelatinizing  when  boiled. 

PEGMATITE — A  variety  of  granite  rock. 

PELARGpNIC  ACID  (C9H18O2)— A  product  of  the  oxidation 
of  oleic  acid  and  contained  naturally  in  the  volatile  oil  of 
Pelargonium  roseum. 

PENNYROYAL  (HEDEOMA)  OIL  is  distilled  from  the  leaves 
and  tops  of  Mentha  pulegium,  and  is  a  pale  yellowish,  limpid, 
essential  oil  of  mint-like  odour,  containing  a  ketonic  sub- 
stance named  pulegone  (C10H16O),  of  which  it  contains 
about  80  per  cent. ;  sp.  gr.  is  0.93  to  0-96,  and  rotation 
+  1 3°  to  +  35°.  It  is  produced  in  Spain,  Southern  France, 
and  Africa,  and  is  used  in  medicine  and  as  an  insectifuge. 

PENTANE — See  Hydrocarbons,  p.  250. 

PENTOSANS — Derivatives  of  the  hexoses,  such  as  arabinose 
and  xylose,  present  in  many  plants.  They  are  removable 
from  cotton  by  treatment  with  5  parts  of  cold  17  per  cent, 
solution  of  sodium  hydroxide. 

PEPPEE  OIL — Extracted  from  common  pepper  (Piper  nigrum) 
by  solvents.  It  is  yellowish,  volatile,  soluble  in  alcohol 
and  ether,  and  contains  phellandrene,  cadinene,  and  dipen- 
tene.  Its  sp.  gr.  varies  from  0*87  to  0*91,  and  it  exhibits 
an  optical  rotation  of  from  -  5°  to  +  12°. 

PEPPERMINT  (OIL  OF)— The  essential  oil  obtained  by  dis- 
tilling the  leaves  and  tops  of  the  Mentha  piperita.  It 
contains  from  45  to  90  per  cent,  of  menthol  (C10H20O),  and 
has  a  sp.  gr.  of  0-9  to  0-92,  and  rotation  -  22°  to  -  42°,  ac- 
cording to  the  variety.  Its  menthol  content  deposits  upon 
cooling.  There  are  several  varieties,  including  English, 


368  PEPPERMINT  (OIL  OF)— PERFUMES 

PEPPERMINT  (OIL  OF)  (Continued)— 

Italian,  American,  Chinese,  and  Japanese  productions. 
The  English  and  American  oils  contain  from  50  to  69  per 
cent,  menthol,  have  a  sp.  gr.  of  from  0-90  to  0*91,  optical 
rotation  -  25°  to  —  29*5°,  and  refractive  index  1*459  to  1*464. 
The  Chinese  oil  is  light  brown  in  colour,  of  rather  dis- 
agreeable odour  and  bitter  taste  ;  its  sp.  gr.  is  0*909,  and  it 
contains  about  70*57  free  menthol. 

The  Japanese  oil  contains  from  73  to  83  per  cent,  free 
menthol. 

The  American  oil  is  the  best  adapted  for  perfumery. 

PEPSIN — The  digestive  ferment  of  gastric  juice  which  is 
active  only  in  a  dilute  acid  environment,  hydrochloric  acid 
of  from  0-08  to  0*2  per  cent,  strength  being  more  favourable 
than  lactic  or  acetic  acid.  Neutralization  suspends  its 
action.  It  is  secreted  in  certain  glands  of  the  stomach  and 
it  is  by  its  agency  that  albuminoids,  etc.,  partaken  as  foods 
are  rendered  assimilable  as  peptones. 

The  "pepsin  "  preparation  of  commerce  is  obtained  from 
the  glandular  layer  of  pigs'  or  calves'  stomachs.  Pepsin 
is  a  nearly  white  amorphous  substance,  insoluble  in  alcohol, 
but  very  soluble  in  dilute  acids  and  glycerine.  Its  solutions 
are  coagulated  by  boiling,  and  it  then  loses  its  digestive 
power.  It  is  sometimes  used  as  a  substitute  for  rennet. 

PEPTONES  result  from  the  enzyme  action  of  pepsin  in  the 
juices  of  the  stomach  upon  the  albuminous  matters  par- 
taken of  as  food.  They  are  soluble  in  water,  diffuse  readily 
through  vegetable  parchment  and  are  not  coagulated  upon 
heating,  so  that  they  are  in  the  best  state  for  assimilation 
in  the  human  economy. 

PERBORATE  OF  SODIUM— See  Sodium  Compounds. 

PERBORIN — Perborate  of  sodium. 

PERCHLO RATES — See  Chlorine  Compounds,  p.  112. 

PERCOLATE — To  filter  or  pass  through,  as,  when  making 
drinking- coffee,  the  dry  coffee  is  percolated  by  hot  water. 

PERFUMES — Preparations  of  a  volatile  nature  consisting  for 
the  most  part  of  odoriferous  substances  dissolved  in 
alcohol.  Some  of  the  better  known  perfumes  are  obtained 
by  distilling  the  flowers  or  flower-petals  of  plants  with 
water — attar  of  roses,  for  example — while  others  are  ex- 
tracted therefrom  by  means  of  solvents  such  as  light 
petroleum  spirit  or  alcohol,  the  solvent  being  afterwards 
evaporated  by  distillation  in  a  vacuum.  Yet  others,  such 
as  the  tuberose  and  jonquil,  the  delicacy  of  which  may  be 


PERFUMES  369 

PEEFUMES  (Continued)— 

impaired  by  the  distillation  process  or  solvent  action,  are 
obtained  by  "  enfleurage " — a  method  which  consists  in 
pressing  the  flowers  against  a  layer  of  cold  fat,  such  as 
lard  or  petroleum  jelly  spread  over  glass  plates,  or  by 
drawing  warm,  moist  air  through  the  flowers  and  passing 
the  current  charged  with  the  odoriferous  principles  over 
fatty  layers,  from  which  the  perfume  is  subsequently  ex- 
tracted by  strong  alcohol.  The  subsequent  evaporation  of 
the  alcohol  yields  the  "  quintessences  "  as  residual  products. 

Ethyl  butyrate  is  the  odoriferous  constituent  of  the  pine- 
apple ;  the  pear  owes  its  fragrance  to  amyl  acetate,  and 
the  apple  to  the  amyl  esters  of  formic,  acetic,  and  hexoic 
acids.  Coumarin,  to  which  the  Tonquin  bean  owes  its 
fragrance,  is  now  made  artificially ;  so  also  vanillin,  which 
gives  its  pleasant  odour  to  the  vanilla  pod  and  is  now 
largely  made  from  eugenol  (the  chief  constituent  of  oil  of 
cloves). 

An  artificial  essence  of  violets  named  ionone  is  made 
from  citral  (to  which  the  odour  of  lemons  and  lemon  grass  is 
due),  and  there  are  many  synthetically  prepared  perfumes, 
as  distinct  from  those  derived  from  flowers,  or  made  in 
imitation  of  natural  products,  as,  for  example,  so-called 
"  heliotropin,"  sold  as  "  white  heliotrope."  So,  again,  a 
ketonic  substance  named  irone  is  a  fragrant  oil  made  from 
the  root  of  iris  (orris),  having  the  odour  of  the  violet. 

Among  the  new  synthetic  perfumes,  may  be  mentioned 
"  fragasol,"  which  is  the  butyl  ether  of  beta-naphthol, 
analogous  to  yara-yara  and  neroline,  which  are  the  methyl 
and  ethyl  ethers  respectively. 

"  Benzilisoeugenol "  has  a  fine  carnation  odour,  and 
"  rhodinol,"  or  rose-aldehyde,  is  probably  a  mixture  of 
aldehydes  used  in  the  manufacture  of  artificial  attar  of 
roses. 

Stysolyl  acetate  has  the  perfume  of  the  calyx  of  the  rose, 
and  amyl  benzyloxide,  which  has  a  marked  gardenia  odour, 
is  used  for  perfuming  soaps,  a  trace  of  methyl  para-cresol 
improving  it. 

Some  of  the  essential  oils  constituting  the  bases  of  per- 
fumes and  essences,  are  obtained  by  pressure  of  the  fruit 
rinds  containing  them,  as,  for  example,  the  orange,  lemon, 
and  bergamot  oils  ;  and  many  others  such  as  eucalyptus 
oil,  camphor  oil,  and  the  terpenes  are  commercially  avail- 
able in  large  quantities,  and  used  either  alone  or  in  com- 
bination with  other  extractives  in  compounding  various 
perfumes. 

24 


370  PERFUMES—"  PERMUTIT  " 

PERFUMES  (Continued)— 

Apart  from  the  essential  oils  used  in  making  perfumes 
and  soaps,  large  quantities  are  used  in  compounding  such 
drinks  as  lemonade  and  sundry  alcoholic  liqueurs,  and  for 
flavouring  purposes,  in  cooking  and  confectionery,  and  in 
medicine,  so  that  the  trade  in  these  oils,  and  the  perfumes 
made  from  them,  is  one  of  large  dimensions  and  importance. 
(See  also  Odour  Theory.) 

PERICLASE — A  native  magnesium  oxide  (MgO). 

PERILLA  OIL— An  essential  oil  from  the  seeds  of  Perilla 
ocimoides.  The  yield  is  from  33  to  35  per  cent.,  the  oil 
being  of  a  greenish -yellow  or  brownish  colour.  It  has  a 
sp.  gr.  0-932  to  0-945,  saponification  value  about  192, 
iodine  value  187  to  202,  and  refractive  index  1-484.  It  is 
soluble  in  alcohol  and  ether,  and  is  used  as  a  substitute 
for  linseed  oil  in  making  varnishes,  and  to  some  extent 
as  an  edible  oil  in  Japan  and  China.  The  oil  from 
P.  nankinensis  is  stated  to  result  from  the  decomposition 
of  a  glucoside  in  the  leaves,  and  to  contain  20  to  30  per 
cent,  limonene,  44  to  57  per  cent,  perillic  aldehyde,  and 
some  pinene. 

PERIODIC  LAW— See  Elements. 
PERMANENT  WHITE — See  Barium,  p.  49. 
PERMANGANATES— See  Manganese,  p.  306. 

PERNAMBUCO  (Lima  wood)— A  red  wood  from  Ccesalpinia 
bijuga,  which  yields  a  red  dye  extract. 

"  PERMUTIT  " — A  number  of  preparations,  called  "  permutits," 
are  artificially  produced  silicates,  capable  of  exchanging 
their  basic  constituents  when  placed  in  certain  solutions; 
so  that  when  employed  for  softening  water  an  exchange 
takes  place,  the  soda  of  the  "  permutit "  passing  into  the 
water  and  being  replaced  by  the  lime  and  magnesia  (the 
hardening  constituents)  of  the  water. 

The  general  method  of  preparation  consists  in  melting 
china  clay  (kaolin)  with  quartz  and  sodium  carbonate,  and 
washing  with  water,  the  product  being  a  double  silicate  of 
soda  and  alumina,  containing  about  46  per  cent,  of  SiO2, 
22  per  cent,  of  A12O3,  13-6  per  cent.  Na2O,  and  18-4  per 
cent.  H2O.  The  permutit  is  revivified  by  passing  a  fairly 
strong  solution  of  common  salt  through  it,  which  restores 
it  to  its  original  constitution,  so  that  after  washing  it  with 
water,  it  can  be  used  again  for  softening  further  quantities 
of  hard  water. 


PEROXIDES— PETROLEUM  371 

PEROXIDE — This  term  indicates  an  oxide  of  higher  degree 
than  the  ordinary  oxide;  for  example,  barium  oxide  (BaO)  is 
the  ordinary  barium  oxide,  whereas  the  peroxide  (dioxide)  is 
BaO2. 

There  are  some  organic  peroxides,  among  which  may  be 
mentioned  acetyl  peroxide,  (C2H3O)2O2  (an  explosive  body 
prepared  from  acetic  anhydride  by  the  action  of  barium 
dioxide) ;  ethyl  hydrogen  peroxide,  C2H6O2,  and  acetone 
peroxide,  (C3H6O2)2,  both  of  which  are  more  or  less  un- 
stable, and  are  made  by  the  agency  of  hydrogen  peroxide 
in  presence  of  potassium  hydroxide. 

PEROXIDE  OP  HYDROGEN— See  Hydrogen,  p.  253. 

PEROXIDE  OF  SODIUM — See  Sodium  Compounds. 

PERRY — Fermented  juice  of  pears. 

PERSIAN  BARK — See  Cascara  Sagrada. 

PERU  BALSAM— See  Balsams. 

PERUVIAN  BARK— See  Quinine. 

PETALITE — A  native  silicate  of  aluminium  and  lithium. 

PETIT-GRAIN  OIL — Distilled  from  the  leaves  and  unripe 
fruit  of  Citrus  bigaradia,  resembling  neroli  oil.  It  is  yellow- 
ish in  colour,  is  soluble  in  alcohol  and  ether,  has  a  sp.  gr. 
of  from  0-89  to  0-90,  and  is  used  in  perfumery. 

PETROL — Fractional  distillates  from  petroleum,  or  "cracked" 
petroleum  products,  with  or  without  admixture  with  benzol, 
ranging  in  boiling-point  from  50°  to  200°  C.  The  better 
qualities  of  petrol  are  used  in  common  with  gasoline  for  pro- 
ducing "air-gas"  for  illumination  purposes.  (See  Gasoline.) 

PETROLATUM — Petroleum  jelly  ;  vaseline. 

PETROLEUM  (rock  or  mineral  oil)  is  a  natural,  dark-coloured, 
oil-like  deposit  of  hydrocarbon  character,  sometimes  occur- 
ring in  beds  or  lakes,  as  in  Trinidad,  and  at  other  times 
flowing  from  clefts  of  rocks  or  from  deep  wells,  as  in  the 
northern  parts  of  the  United  States,  particularly  between 
Pittsburg  and  Lake  Erie.  Deposits  also  occur  in  parts  of 
Germany,  Persia,  Roumania,  Galicia,  Burmah,  the  Crimea, 
and  have  been  recently  discovered  at  Hardstoft  in  Derby- 
shire, also  in  Norfolk  and  Nottinghamshire. 

The  petroleum  from  all  fields  consists  in  the  main  of  so- 
called  paraffin  hydrocarbons,  associated  with  small  pro- 
portions of  compounds  containing  oxygen,  nitrogen,  and 
sulphur,  and  are  worked  on  a  large  scale  as  the  source  of  a 
number  of  valuable  products. 

The  hydrocarbons  of  many  of  the  natural  petroleums  are 
of  the  same  series,  although  contained  in  varying  proper- 


372  PETROLEUM 

PETROLEUM  (Continued)— 

tions ;  but  while  the  American  oils  consist  in  the  main  of 
paraffin  hydrocarbons,  the  Russian  oil  con  tains  large  amounts 
of  the  general  formula  CWH2«  (such  as  C6H12,  C7H14,  etc.), 
known  as  naphthenes,  which  are  isomeric  with  the  olefines. 
The  oil  recently  discovered,  and  now  being  produced,  at 
Hardstoft,  in  this  country,  contains  naphthenes,  and  an 
early  sample  furnished  upon  examination  7  per  cent,  motor 
spirit,  40  per  cent,  burning  oil,  20  per  cent,  gas  oil,  30  per 
cent,  lubricating  oil,  and  3  per  cent,  solid  paraffin. 

Crude  petroleum,  which  is  used  to  some  extent  as  a  sub- 
stitute for  coal  in  locomotives,  has  a  sp.  gr.  ranging  from 
078  to  0-97  or  more,  and  by  fractional  distillation  yields  a 
number  of  products,  including  the  so-called  petroleum  ether, 
benzine,  gasoline,  kerosene,  paraffin  oil,  heavy  lubricating 
oils,  and  petroleum  jelly,  which  are  described  under  their 
respective  names.  The  various  fractional  distillates  are 
further  separated  and  refined  by  redistillation. 

The  benzine  produced  from  many  crude  petroleums  re- 
quires no  chemical  treatment,  and  is  largely  used  as  motor 
spirit;  but  the  "  white  spirit "  and  "  kerosene  "  which  follow 
(and  are  used  in  lamps)  are  refined  by  filtration  through 
powdered  bauxite  or  fuller's  earth,  which  removes  the 
sulphur  compounds  and  can  be  regenerated  for  further 
use  by  heating. 

Paraffin  wax  is  separated  from  the  higher  distillate  portion 
containing  it,  by  cooling  to  45°  F.,  and  squeezing  out  the 
heavy  associated  oil,  which  is  utilized  as  lubricating  oil 
after  redistillation. 

Coke  or  pitch  is  finally  left  in  the  retort,  and,  the  former 
being  very  pure,  finds  a  ready  sale  to  the  manufacturers  of 
electric  light  carbons  and  carbon  crucibles,  whilst  the  pitch 
can  be  used  either  as  fuel  or  can  be  oxidized  or  sulphurized, 
and  thus  utilized  in  making  artificial  asphalt. 

When  petroleum  oils  are  "cracked"  at  about  700°  to 
750°  C.,  most  of  them  yield  a  distillate  containing  toluol, 
and  large  supplies  of  that  material  were  thus  obtained 
during  the  Great  War,  and  supplies  of  so-called  motor  spirit 
are  made  by  "cracking"  the  heavier  oils. 

Fatty  acids  can  be  obtained  from  petroleum  hydro- 
carbons by  catalytic  oxidation,  using  air  or  oxygen  in 
association  with  certain  lead  or  mercuric  compounds 
(which  apparently  dissolve  in  the  products  of  the  process) 
at  a  temperature  of  115°  to  120°  C.,  and  under  a  pressure 
of  three  atmospheres,  with  agitation  in  the  presence  of 
water  for  some  seven  hours.  The  oxidation  products  have 
been  stated  at  from  7  to  20  per  cent,  water,  25  to  40  per 


PETROLEUM— PHELLANDRENE  373 

PETROLEUM  (Continued)— 

cent,  lower  fatty  acids,  with  small  amounts  of  aliphatic 
aldehydes  and  ketones,  from  50  to  78  per  cent,  of  higher 
fatty  acids,  and  10  to  15  per  cent,  of  unsaponifiable  matters. 
The  products  are  fractionated  by  distillation,  and  the  higher 
fatty  acids  thus  obtained  mixed  with  10  to  20  per  cent,  of 
tallow  or  cocoa-nut  oil  fatty  acids  to  make  soap.  Fatty 
acids  can  also  be  obtained  by  the  chlorination  of  certain 
paraffin  hydrocarbons  at  160°  C.,  subsequent  elimination  of 
the  hydrogen  chloride  thus  produced,  and  oxidation  of  the 
resulting  olefine  by  means  of  potassium  permanganate  or 
ozone. 

American  petroleum  (U.S.A.)  is  said  to  yield  on  average 
the  following  fractions  upon  distillation  :  light  naphtha  1 7, 
kerosene  50  to  54,  lubricating  oil  17,  paraffin  wax  2,  and 
loss  10. 

Petroleum  is  commonly  supposed  to  be  derived  from 
organic  matters  by  chemical  changes  operating  over  long 
periods  of  time,  and  as  all  petroleums  contain  so-called 
algae  wax,  one  theory  favours  enormous  masses  of  algae 
accumulated  over  immense  periods  of  time  in  marshy  areas 
as  its  material  origin. 

The  total  output  of  petroleum  in  1920  was  over  97 
million  tons,  and  of  this  the  British  Empire  controlled  only 
4  per  cent. 

PETROLEUM  ETHER— The  fractional  distillate  from  petro- 
leum, which  boils  at  from  40°  to  70°  C.,  and  of  sp.  gr. 
0-635  t°  0*660,  purified  by  washing  with  sulphuric  acid, 
then  with  soda,  and  subsequent  redistillation,  and  used  as  a 
volatile  solvent.  It  contains  a  large  proportion  of  the  lower 
paraffin  hydrocarbons  (heptane,  hexane,  etc.). 

PETROLEUM  JELLY  is  an  emulsion  of  soft  paraffins  dis- 
persed in  heavy  oils,  the  viscosity  of  which  increases 
gradually  with  decreasing  temperature  until  the  "  gel " 
state  is  reached.  There  is  no  separation  of  crystalline  wax, 
which  is  only  obtained  upon  distillation  of  the  jelly,  in  the 
distillate. 

It  is  made  from  the  still  residue  left  after  the  distillation 
of  petroleum,  being  subsequently  decolourized  by  filtration 
in  a  heated  state  through  fuller's  earth  or  animal  charcoal, 
and  is  used  as  a  lubricant,  leather  grease,  in  making  polishes, 
as  a  rust  preventive,  and  as  a  perfume  extractor  in  enfleur- 
age.  (See  Petroleum.) 

PEWTER— See  Tin. 

PHELLANDRENE — A  terpene  constituent  of  eucalyptus  oil, 
which  boils  at  171°  C.  (See  Essential  Oils  and  Terpenes.) 


374  PHENA  CETINE— PHENOLS 

PHENACETINE  (C10H13O2N)— A  colourless  crystalline  com- 
pound  (acetophenetidine),  soluble  in  water,  alcohol,  and 
ether;  used  as  a  remedy  for  neuralgia;  melting-point,  135°  C. 

PHENACITE— Glucinum(orberyllium)ortho-silicate(Gl2SiO4), 
found  in  Colorado. 

PHENANTHRENE — A  substance  isomeric  with  anthracene, 
which  it  accompanies  in  coal  tar.  It  melts  at  99°  C.,  boils 
at  340°  C.,  and  is  used  in  making  blacks. 

PHENAZONE— See  Antipyrine. 

PHENOLOIDS — The  more  active  principles  of  so-called  "  high- 
boiling  acids  "  of  phenolic  and  cresolic  character,  obtained 
in  the  redistillation  of  tar  from  blast  furnaces  and  coke 
ovens. 

The  exact  constitution  of  the  higher  phenols  is  largely 
a  matter  of  speculation,  but  they  exhibit  relatively  high 
boiling-points  as  compared  with  the  cresols,  being  found 
in  the  residue  obtained  after  separation  of  the  cresols 
by  fractional  distillation ;  but  it  is  believed  that  they 
consist  chiefly  of  xylenols  or  dimethylhydroxybenzenes 
(C6H3(CH3)2OH).  They  exhibit  greater  bactericidal  pro- 
perties than  the  cresols,  and  are  less  poisonous  than  phenol. 
Phenoloids  are  used  not  only  in  making  disinfectants, 
sheep  dips,  larvicides,  and  weed-killers,  but  also  in  making 
cutting  compounds  for  engineering  purposes,  as  they  form 
good  emulsions  in  aqueous  soap  solutions. 

PHENOLPHTHALEIN  (Dihydroxy  -  diphenyl  -  phthalide, 
(C6H4OH)3.CO.C6H4CO) — A  creamy-white  organic  pow- 
der used  as  a  purgative,  as  a  dye  base,  and  as  an  indi- 
cator (like  litmus)  in  chemical  reactions.  A  solution  of 
|  per  cent,  in  equal  parts  of  alcohol  and  water  gives  a 
strong  pink  colour  when  rendered  alkaline ;  melting-point, 
250°  C.  (See  Volumetric  Analyses.) 

PHENOLS — A  series  of  bodies,  some  being  liquids  and  some 
solids,  many  of  which  have  antiseptic  properties.  Ordinary 
phenol  or  carbolic  acid  (C6H6O)  is  the  active  principle  of 
crude  carbolic  acid  as  obtained  from  coal-tar  distillation. 
In  the  pure  state  it  is  a  white,  poisonous,  deliquescent, 
crystalline  substance,  of  sp.  gr.  1*08,  which  melts  at  42°  C.; 
is  soluble  in  water  (i  :  15)  at  16°  C.,  and  readily  soluble 
in  alcohol.  It  is  used  in  the  preparation  of  antiseptics, 
disinfectants,  dyes,  and  explosives.  Other  phenolic  bodies 
are  cresol  (CrH8O),  xylenol  (C8H10O),  cumenol  (C^H^O), 
carvacrol  (C10H14O),  and  thymol  (C10H14O).  (See  also 
Carbolic  Acid.) 


PHENYL— PHOSPHOR  US  375 

PHENYL  (C6H5) — The  benzene  nucleus  or  radical,  as,  for 
example,  in  phenol  (C6H5HO). 

PHENYLAMINE  (C6H5NH2)— See  Aniline. 

PHLORIDZIN  (C21H24O10)— A  glucoside  found  in  the  root-bark 
of  some  fruit"  trees  (such  as  the  apple,  pear,  plum,  and 
cherry),  which  upon  hydrolysis  yields  phloretin  (C15H14O5) 
and  grape  sugar.  It  is  soluble  in  alcohol  and  hot  water. 

PHOSGENE— See  Carbonyl  Chloride. 

PHOSPHATE  ROCK— See  Coprolites  and  Phosphorus. 

PHOSPHATES— See  Phosphorus. 

PHOSPHATIC;  MANURES— See  Fertilizers,  Superphosphate 
of  Lime,  and  Slag. 

PHOSPHIDES— See  Phosphorus. 

PHOSPHINE— See  Phosphorus. 

PHOSPHINES  (Organic) — Feebly  basic  compounds  prepared 
from  phosphoretted  hydrogen  (phosphine)  (PH3)  by  the 
substitution  of  hydrogen  with  alkyl  radicals — for  example, 
triethyl  phosphine  P(C2H5)3.  They  correspond  closely  to 
the  amines  in  composition. 

PHOSPHITES — See  Phosphorus. 

PHOSPHOR  BRONZE— An  alloy  with  a  low  coefficient  of 
friction,  used  as  a  substitute  for  bronze  and  gun-metal  in 
gearings,  bearings,  wire  ropes,  etc.,  composed  of  copper  and 
tin  fluxed  with  a  variable  quantity  (up  to  i  per  cent.)  of 
phosphorus,  which  is  generally  added  in  the  form  of  copper 
phosphide  or  tin  phosphide. 

PHOSPHORETTED  HYDROGEN  or  PHOSPHINE— See  Phos- 
phorus, p.  377. 

PHOSPHORIC  ACID— See  Phosphorus. 

PHOSPHORITE  (Rock  Phosphate  of  Calcium) — A  variety  of 
apatite. 

PHOSPHORUS  (P)  and  its  Compounds— Atomic  weight,  31  ; 
melting-point,  44°  C.  This  element  does  not  occur  in 
nature  in  its  free  state,  but  abounds  in  combination  with 
calcium  and  oxygen  in  the  seeds  of  plants  and  in  soils,  its 
presence  in  the  latter  being  derived  from  the  disintegration 
of  rocks.  Plants  require  phosphates  as  an  essential  to  their 
proper  growth  and  development,  and  the  animal  kingdom 
obtains  its  supply  in  turn  from  vegetable  life.  Phosphorus 
in  various  combinations  is  also  present  in  many  of  the 
animal  tissues,  including  brain  matter,  and  the  bones  owe 
their  rigidity  to  calcium  phosphate,  which  makes  up  60  per 
cent,  of  their  substance.  Bone  ash,  indeed,  consisting  as 


376  PHOSPHORUS 

PHOSPHORUS  (Continued] - 

it  does,  in  the  main,  of  that  substance,  is  one  of  the  chief 
sources  of  phosphorus.  (See  Bones.)  In  various  com- 
binations as  phosphate,  it  is  present  in  the  minerals 
sombrerite  (Ca3(PO4)2).  apatite  (3Ca3(PO4)2,CaF2),  wavellite 
(2A12(PO4)2,A12(HO)6,9H2O),  and  in  coprolites.  (See  Co- 
prolites.) 

Phosphorus  is  made  from  bone  ash  or  sombrerite  by 
treatment  with  sulphuric  acid  of  sp.  gr.  about  1*5,  when  the 
following  interaction  takes  place  : 

Ca3(PO4)2  +  3H2SO4=  3CaSO4  +  2H3PO4 

—that  is  to  say,  insoluble  calcium  sulphate  and  phosphoric 
acid  (in  solution)  are  produced,  and  after  filtration  of  the 
mixture,  the  liquid  nitrate  is  concentrated  by  evaporation 
and  yields  the  acid  in  crystalline  form  of  a  deliquescent 
nature.  From  the  acid  so  prepared,  phosphorus  may  be 
obtained  by  mixing  it  with  powdered  charcoal,  heating,  and 
subsequent  distillation ;  at  first,  the  phosphoric  acid  is  broken 
up  into  water  and  meta-phosphoric  acid  as  follows  : 

H3P04=H20  +  HP03, 

and  at  a  later  stage  there  is  a  further  change  by  which  this 
acid  is  decomposed  as  expressed  in  the  equation : 

4HPO3+  i2C  =  I2CO  (carbon  monoxide) 
+  2H2  (hydrogen)  +  4?  (phosphorus), 

the  phosphorus  being  condensed  in  dark  yellow  drops  under 
water,  in  which  it  subsequently  solidifies. 

In  the  pure  state,  phosphorus  is  a  slightly  yellowish- 
white,  semi-transparent,  and  wax-like  substance  which  takes 
fire  when  warmed  and  exposed  to  the  air,  so  that  it  has  to 
be  kept  submerged  in  water.  In  its  ordinary  form  it  is 
very  poisonous.  It  has  a  sp.  gr.  of  1*83,  and  is  soluble  in 
carbon  disulphide  (CS2)  from  which  it  may  be  obtained 
upon  evaporation,  in  the  form  of  colourless  crystals.  It 
may  also  be  sublimated  in  vacuo  and  obtained  in  beautiful 
crystals. 

Phosphorus  forms  many  compounds,  and,  in  the  form  of 
soluble  phosphates,  phosphoric  acid  enters  into  the  com- 
position of  many  medicines,  such  as  chemical  foods  and 
nerve  stimulants.  They  are  also  used  in  the  dyeing  and 
bleaching  trades,  the  fireproofing  of  woods,  and  in  sugar- 
refining. 


PHOSPHORUS  377 

PHOSPHORUS  (Continued)— 

The  natural  phosphates,  with  or  without  treatment,  are 
largely  used  in  agriculture  as  fertilizers. 

Phosphorus  is  allotropic  —  that  is  to  say,  it  can  be  made 
to  assume  more  than  one  form.  When  heated  to  between 
240°  and  250°  C.  out  of  contact  with  the  air,  it  passes  into 
a  red  form,  which  has  a  sp.  gr.  of  2-3,  and,  unlike  the 
ordinary  yellow  phosphorus,  is  not  luminous  in  the  dark, 
is  not  poisonous,  and  is  largely  used  in  connection  with  the 
use  of  matches.  These  are  tipped  with  a  mixture  of  potas- 
sium chlorate,  potassium  dichromate,  red-lead,  and  antimony 
sulphide,  and  when  rubbed  over  a  surface  of  red  phosphorus 
and  antimony  sulphide  (as  spread  over  the  sides  of  the 
safety-match  boxes),  take  fire  by  friction.  In  the  preparation 
of  paraffin  matches,  the  yellow  phosphorus  is  employed. 

Phosphorus  is  also  used  in  the  preparation  of  rat-poison 
and  in  the  manufacture  of  phosphor  bronze. 

Phosphorus  forms  several  compounds  with  hydrogen, 
the  better  known  of  which  is  hydrogen  phosphide  (PH3) 
—  also  known  as  phosphine.  It  is  formed  when  red  phos- 
phorus is  gently  heated  in  a  current  of  hydrogen  gas,  and 
is  also  produced  by  the  action  of  water  upon  calcium 
phosphide  — 

3Ca2P2  +  i2H2O  =  6CaH2O2  +  4PH3  +  2P. 


It  is  a  colourless,  highly  poisonous  gas,  soluble  in  alcohol 
and  ether,  of  offensive  garlic-like  odour,  and  takes  fire  at  a 
temperature  below  that  of  boiling  water. 

Calcium  phosphide  is  employed  in  the  construction  of 
drain-testers,  and  the  action  of  water  upon  that  substance 
finds  practical  employment  also  in  the  marine  appliance 
known  as  Holmes's  signal.  In  the  case  of  the  drain-testers 
it  is  the  distinctive  odour  of  the  gas  that  enables  the 
operator  to  detect  leakages  in  drains,  whilst  in  the  case  of 
Holmes's  signal,  the  phosphoretted  hydrogen  ignites  and 
burns,  giving  a  considerable  illumination. 

Hypophosphorous  Acid  (H3PO2)  is  a  crystalline  body 
which  melts  at  17*4°  C.,  and  is  obtained  by  decomposing 
its  barium  salt  with  sulphuric  acid,  the  barium  compound 
in  its  turn  being  prepared  by  boiling  phosphorus  in  a 
solution  of  barium  hydroxide. 

Phosphoric  Acid  (ortho-phosphoric  acid,  H3PO4),  prepared 
as  already  described  (p.  376),  is  put  up  in  various  forms  — 
viz.,  as  a  liquid  of  sp.  gr.  1*5,  also  in  paste  containing  from 
40  to  50  per  cent.,  and  in  crystalline  form  with  a  melting- 


378  PHOSPHORUS  COMPOUNDS 

PHOSPHORUS  (Continued)— 

point  of  38-6°  C.  Its  salts  are  obtained  by  neutralization 
with  alkali  to  the  required  point  and  crystallization.  It 
finds  employment  in  the  sugar  industry,  etc. 

There  is  a  pyrolitic  method  of  producing  phosphoric 
acid — viz.,  by  smelting  mixtures  of  phosphate  rock,  sand, 
and  coke,  and  collecting  the  fumes  of  the  generated  acid 
by  means  of  the  Cottrell  precipitator.  (See  Cottrell  Pre- 
cipitating Plant.)  This  process  is  stated  to  be  of  promising 
character,  and  likely  to  prove  much  less  costly  than  the 
sulphuric  acid  process. 

Phosphorous  Acid  (H3PO3)  is  a  white  crystalline  body 
with  a  melting-point  of  70-1°  C.,  formed  by  dissolving 
phosphorus  oxide  in  water  or  by  the  action  of  water  upon 
phosphorus  trichloride — 

PC13  +  3H2O  =  3HC1  +  H3P03. 
It  is  dibasic  and  forms  two  classes  of  salts. 

Meta-phosphoric  Acid  (Glacial  Phosphoric  Acid,  HPO3) 
is  a  highly  deliquescent  glacial  mass,  which  results  from 
the  deliquescence  of  phosphorus  pentoxide,  and  can  be 
obtained  by  heating  ortho-phosphoric  acid  to  redness,  by 
which  it  loses  a  molecule  of  water  : 

H3PO4-H2O=HPO3. 
It  is  used  in  pharmacy  and  medicine. 

Pyrophosphoric  Acid  (H4P2O7)  is  a  white  crystalline 
body,  soluble  in  water,  which  can  be  prepared  in  a  number 
of  ways,  as,  for  example,  by  heating  the  ortho-acid  to 
213°  C.,  when  it  loses  a  molecule  of  water,  yielding  the 
pyro-acid — 

2H3P04-H20  =  H4P207. 

All  these  acids  form  a  number  of  salts,  many  of  which  are 
used  in  the  arts  and  manufactures. 

There  are  a  number  of  oxides  of  phosphorus,  of  which 
the  more  important  are  the  trioxide  and  the  pentoxide. 

Phosphorus  Trioxide  (P4O6)  is  formed  by  burning  phos- 
phorus in  a  limited  current  of  dry  air,  and  is  a  white,  non- 
crystalline  powder  which  melts  at  22-5°  C. 

Phosphorus  Pentoxide  (P2O5)  is  formed  when  phosphorus 
is  burned  in  excess  of  air  or  oxygen,  and  is  a  white  powder 
which  is  volatile  and  may  be  sublimed.  It  is  used  chemic- 
ally as  a  dehydrating  agent,  having  a  great  affinity  for 
water. 


PHOSPHOR  US—PILOCA  RPINE  379 

PHOSPHORUS  (Continued)— 

Phospho-molybdic  Acid  (H3PO4,i2MoO3)  —  A  yellow, 
crystalline  substance  soluble  in  water,  used  chemically  as 
a  reagent  in  the  examination  of  alkaloids. 

Phosphorus  Trichloride  (PC13)  is  a  colourless,  fuming 
liquid,  and  the  pentachloride  (PC15)  is  a  yellow,  crystalline 
body,  both  of  which  are  made  by  the  action  of  chlorine 
upon  phosphorus,  and  are  used  as  chlorinating  agents  in 
organic  chemistry.  Both  are  soluble  in  carbon  disulphide. 

Other  compounds  of  phosphorus  include  phosphonium 
chloride  (PH4C1),  phosphonium  bromide  (PH4Br),  phos- 
phonium iodide  (PH4I)  (all  of  which  are  crystalline  bodies), 
and  two  fluorides  (PF3  and  PF5). 

PHOTO  GEN— A  name  sometimes  given  to  the  light  hydro- 
carbon oils  (obtained  from  the  distillation  of  coal,  peat,  and 
shale  at  low  temperatures)  which  are  used  for  burning  in 
lamps. 

PHOTOGRAPHY— See  Light,  p.  294. 

PHTHALIC  ACID  (C8H6O4  or  C6H4(C92H)2)— A  colourless 
crystalline  substance,  readily  soluble  in  water,  alcohol,  and 
ether,  which  is  made  commercially  by  oxidizing  naphthalene 
with  fuming  sulphuric  acid  in  the  presence  of  a  small 
quantity  of  mercury  at  220°  to  230°  C.  It  melts  at  213°  C. 

PICOLINE  (C5H4N(CH3))  —  One  of  several  homologues  of 
pyridine. 

PICRICACID(C6H2(NO2)3OH)(Tri-nitro-phenol)— Apoisonous, 
lemon-coloured,  crystalline  substance  which  melts  at 
122°  C.  and  is  largely  used  in  the  manufacture  of  explo- 
sives and  as  a  yellow  dye  for  silk  and  wool.  It  is  prepared 
by  the  graduated  action  of  strong  nitric  acid  upon  phenol 
and  by  the  nitration  of  monochlorobenzol  in  the  presence  of 
sulphuric  acid,  etc. 

It  explodes  with  violence  when  heated  or  struck,  is 
soluble  in  alcohol,  and  sparingly  soluble  in  water,  to  which 
it  gives  a  deep  yellow  colour;  melting-point,  122°  C.  (See 
Explosives,  p.  190.) 

PIGMENTS — Insoluble  coloured  substances  used  as  bases  in 
compounding  paints.  The  term  is  more  particularly  applied 
to  mineral  bases  as  distinct  from  organic  colouring  matters 
such  as  dyes  or  stains  which  are  soluble  in  the  vehicles  used. 

PILOCARPINE  (CUH16N202  or  C23H34N4O4)— A  crystalline, 
poisonous  alkaloid  (melting-point,  34°  C.),  soluble  in  water 
and  alcohol,  contained  in  the  leaves  and  stalks  of  jaborandi 


380  PILOCARPINE— PINE-TAR  OIL 

PILOCARPINE  (Continued)— 

(Pilocarpus  pennatifolius) ;  used  in  medicine  an  d  compound- 
ing hair  tonics. 

PIMARIC  ACID  (C20H?0O2)— A  substance  obtained  from 
galipot  resin,  resembling  abietic  acid,  and  of  melting-point 
144°  to  146°  C. 

PIMELITE — Native  green  nickeliferous  silicates. 

PIMENTO  OIL — A  colourless  or  slightly  yellow,  heavy,  volatile 
oil  distilled  from  the  unripe  fruit  of  Myrtus  pimenta  of  the 
West  Indies,  resembling  oil  of  cloves  in  odour.  Sp.  gr., 
1-045  to  I<0555  soluble  in  alcohol  and  ether;  and  used  in 
perfumery  and  for  flavouring. 

The  oil  distilled  from  the  leaves  of  the  plant  yield  about 
i '8  per  cent,  of  eugenol,  from  which  vanillin  can  be  obtained. 

"  PINACYANOL " — A  dyestuff  that  sensitizes  photographic 
plates  far  into  the  red  region  of  the  spectrum. 

"  PINAVERDOL  " — An  isocyanine  dyestuff  used  for  sensitizing 
photographic  plates  through  the  green  and  well  into  the 
red  region  of  the  spectrum. 

PINCHBECK — An  alloy  gold-like  in  appearance  consisting  of 
copper  alloyed  with  zinc  in  varying  proportions — about 
3  oz.  zinc  to  i  Ib.  copper  or  i  part  zinc  and  8  parts  copper. 

PINE  OIL — This  name  is  now  Variously  used,  but  was  origin- 
ally applied  to  the  turpentine-like  oils  obtained  from  pine 
and  fir  trees,  particularly  those  from  the  seeds  and 
needles.  They  vary  in  their  characters,  such  as  their 
odours,  drying  properties,  and  rotatory  powers,  etc.  The 
oil  from  Pinus  pumilio  needles  is  used  in  medicine  and  is 
one  of  the  best  known  of  this  class,  having  an  agreeable 
balsamic  odour,  of  sp.  gr.  0-86^  to  0-875,  an^  rotation 
-  6°  to  -  14°. 

Pine  oil  is  a  name  now  given  in  commerce  also  to  a  crude 
kind  of  turpentine  obtained  from  the  United  States,  and  to 
a  refined  rosin  oil  obtained  as  a  product  of  the  destructive 
distillation  of  rosin. 

PINENE  (Australene)  (C10H16) — A  terpene  constituent  of 
American  turpentine,  pine  oil,  and  some  other  essential 
oils.  Sp.  gr.,  0-8587;  boiling-point,  156°  C. 

PINE-TAR  OIL  is  a  distillate  of  pine  tar  which  darkens  to 
a  reddish-brown  colour  on  keeping.  It  has  a  strong  tarry 
and  sharp  odour,  and  is  a  very  complex  mixture  resulting 
from  the  destructive  distillation  of  the  tar.  Its  average 
sp.  gr.  is  0*970 ;  it  is  soluble  in  turpentine,  and  is  used  in 
ore  concentration  by  the  flotation  process. 


PIPECLAY— PITCH 


381 


PIPECLAY — A  peculiar  variety  of  clay  found  in  Dorsetshire 
and  Devonshire,  used  for  making  tobacco  pipes  and  certain 
kinds  of  pottery. 

PIPER  (Piper  Nigrum) — Black  pepper,  which  yields  an  essential 
oil  containing  terpenes.  (See  Pepper  Oil.  p.  367.) 

PIPERIDINE  (C5HnN)— A  colourless,  liquid  amine,  smelling 
something  like  pepper  and  of  basic  character,  found  i 


in 


pepper  in  association  with  piperic  acid  (C]2H10O4)  as  the 
alkaloid  piperine  (C18H18NO3).  It  boils  at  106°  C,  is 
soluble  in  water  and  alcohol,  and  yields  crystalline  salts. 

PIPERINE— See  Piperidine. 

PIPERITONE— A  ketonic  constituent  of  eucalyptus  oil  yielded 
by  the  Eucalyptus  piperita  and  E.  dives,  and  from  which,  both 
menthol  and  thymol  can  be  prepared  by  processes  of 
reduction. 

PIPERONAL  (Artificial  Heliotrope)— See  Heliotropine. 

PIPETTES,  as  held  in  a  pipette  stand,  are 
shown  in  the  illustration.  .  They  are  glass 
tubes,  with  or  without  bulbs,  used  for 
transferring  given  measures  of  liquid  from 
one  vessel  to  another,  and  are  made  to 
hold  definite  quantities,  such  as  5  c.c., 
10  c.c.,  20  c.c.,  25  c.c.,  50  ex.,  and  100  c.c., 
being  graduated  on  the  stem.  In  practice, 
they  are  filled  up  somewhat  above  the 
graduated  mark,  by  dipping  the  lower  end 
in  the  liquid  and  sucking  up  with  the 
mouth;  then  rapidly  placing  the  finger 
(preferably  moistened)  on  the  top  of  the 
upper  end,  to  close  same  after  the  liquid 
has,  by  release,  reached  the  marking  on 
the  stem. 

PITCH  is  a  generic  name  applied  to  a  number  of  products 
more  or  less  identical  in  character  but  variously  produced. 
Gas-Tar  Pitch  or  Coal-Tar  Pitch  is  the  residue  left  in  the 
retorts  from  the  distillation  of  gas  tar,  and  finds  use  in 
roofing,  as  a  binding  material  in  the  making  of  briquettes 
and  joining  up  wooden  road-paving  blocks,  also  in  making 
a  black,  coarse  varnish,  etc. 

Rosin  Pitch  is  that  left  behind  from  the  destructive  dis- 
tillation of  rosin,  and  can  be  used  for  the  same  purposes. 

There  are  also  varieties  of  pitch  left  behind  from  the 
distillation  of  wood  and  petroleum  oils. 


382  PITCH— PLANT  COLOURING  MATTERS 

PITCH  (Continued)- 

Burgundy  Pitch  is  used  in  medicine,  and  is  the  melted 
resin  of  Abietes  resina,  but  is  not  a  "  pitch"  in  the  same 
sense.  (See  Burgundy  Pitch.) 

PITCH-BLENDE  (Uraninite) — A  native  uranium  oxide  associ- 
ated with  other  uranium  compounds  found  at  St.  Stephen's, 
Cornwall,  and  in  Austria,  Colorado,  and  elsewhere.  It  is  used 
as  the  chief  source  of  radium  and  uranium  compounds. 

PLANT  (Chemical)— See  Chemical  Plant. 

PLANT  COLOURING  MATTERS  occur  in  the  forms  of  so- 
called  "plastid  pigments,"  such  as  chlorophyll,  carotin,  etc. 
(which  are  intimately  associated  with  the  organized  proto- 
plasmic structure  of  plants),  and  the  soluble  "  sap  pig- 
ments," the  latter  class  being  divisible  into  two  main 
classes — viz.,  (i)  derivatives  of  flavone  (flavonal) — some- 
times named  anthoxanthenes — which  are  pale  yellow  or 
colourless  when  in  faintly  acid  solution,  but  bright  yellow 
in  alkaline  solution,  and  (2)  the  anthocyans,  which  are  red 
in  acid  solution,  violet  when  neutral,  and  varying  from  dull 
red  or  reddish-brown  to  purple  and  blue  when  present  in 
the  form  of  alkaline  salts  in  solution. 

Carotin  (carrotene)  is  according  to  one  investigator  a 
hydrocarbon  of  the  composition  C40H56,  which  crystallizes 
in  copper-coloured  leaflets,  absorbs  oxygen  readily  from 
the  air,  and  becomes  converted  into  a  colourless  product. 

It  would  appear  from  chemical  investigations  that,  the 
anthocyan  pigments  are  reduction  products  of  the  yellow 
sap  pigment,  whilst  botanical  work  points  to  the  conclusion 
that  these  anthocyan  pigments  are  present  in  plant  life  in 
positions  that  are  known  as  the  seat  of  oxidizing  influences. 

The  anthocyan  pigment  of  the  pelargonium  has  been 
obtained  in  a  crystalline  condition,  and  many  of  these 
pigments  occur  naturally  in  plants  in  the  form  of  gluco- 
sides. 

The  anthocyans  (anthocyanins)  are  said  to  contain 
similar  nuclei,  no  matter  how  much  they  differ  in  colour, 
and  the  wide  variation  of  tints  is  ascribed  to  slight  differ- 
ences in  constitution  which  leave  the  main  skeleton  intact. 

The  blue  cornflower  yields  a  pigment  identical  with  that 
of  the  red  rose,  named  cyanin,  which  gives  a  chloride  of  the 
composition  C27H31O16C1,  and  upon  heating  this  substance 
with  a  20  per  cent,  solution  of  hydrochloric  acid,  it  is 
hydrolized  into  cyanidin  and  glucose : 

C87H81016C1  +  2H,0  =  CUHUO.C1  +  2C6HU06. 


PLANT  COLOURING  MATTERS— PLATINUM         383 

PLANT  COLOURING  MATTERS  (Continued)— 

The  anthocyanin  of  Salvia  coccinea  is  named  salvianin, 
and  upon  hydrolysis  yields  pelargonidin,  dextrose,  and 
malonic  acid. 

The  red  pigment  of  the  young  leaves  of  the  grape-vine  is 
said  to  be  a  free  anthocyanidin,  probably  identical  with 
oenidin,  the  anthocyanidin  of  the  purple  grape  (Vitis 
vinifera},  although  it  may  appear  in  a  colourless  modifica- 
tion termed  a  leuco-anthocyanin,  in  which  it  appears  to  be 
associated  with  another  substance,  possibly  a  carbohydrate, 
giving  rise  to  anthocyanidin  on  treatment  with  strong  acids. 

Many  of  the  yellow  sap  pigments  were  largely  used  in 
the  past  as  mordant  dyes  before  the  synthetic  colours 
became  available  in  industry,  and  some  of  them,  such  as 
fustic,  are  still  employed. 

The  archil  or  cudbear  group  constitutes  a  class  of  colours 
that  were  also  formerly  of  much  commercial  importance, 
and  are  produced  from  soluble  colourless  substances  which 
are  contained  in  a  variety  of  lichens.  (See  also  Archil, 
Alizarine,  Chlorophyll,  and  Flavone.) 

PLANT  LIFE— See  Vegetation. 

"PLASMON" — A  proprietary  preparation  of  milk  casein  made 
soluble  by  agency  of  alkalies. 

PLASTER  OF  PARIS — See  Calcium  Compounds,  p.  75. 

PLASTICITY — Capability  of  change;  easily  moulded  into 
desired  form. 

PLATINUM  (Ft)  and  its  Compounds — Atomic  weight,  195; 
sp.  gr.,  21*5;  melting-point,  1,755°  C.  Platinum  is  found 
naturally  in  the  metallic  state  in  small  grains  and  nuggets 
in  river  sand  and  alluvial  deposits  in  Brazil,  Borneo, 
California,  Colombia,  New  South  Wales,  Tasmania,  and 
the  Ural  Mountains;  also  as  sperrylite,  etc.,  in  association 
with  some  other  rare  metals  including  palladium,  rhodium, 
ruthenium,  osmium,  and  iridium. 

Up  to  1914  Russia  supplied  over  90  per  cent,  of  the 
world's  supply  of  platinum. 

It  is  of  a  bright  greyish-white  colour,  is  malleable  and 
ductile,  does  not  tarnish  in  the  air,  is  heavier  than  gold,  and 
is  of  low  electric  conductivity.  It  can  be  melted  by  the  oxy- 
hydrogen  flame. 

To  obtain  platinum  from  associated  metals,  it  is  digested 
in  aqua  regia  under  some  pressure,  the  solution  evaporated 
to  dryness  and  the  residue  heated  to  125°  C.  In  this  way, 
any  rhodium  chloride  is  rendered  insoluble,  and  upon 


384  PLATINUM 

PLATINUM  (Continued)— 

extraction  with  water,  acidification  of  the  extract  with 
hydrochloric  acid  and  addition  of  ammonium  chloride,  the 
red  double  ammonium  and  platinum  chloride  (2NH4C1, 
PtCl4)  is  produced  and  crystallized  out ;  the  corresponding 
iridium  salt,  so  far  as  it  is  present,  being  left  in  the 
mother -liquor.  From  this,  spongy  platinum  is  obtained 
upon  ignition,  and  may  be  hammered  into  a  concrete  mass 
or  melted  in  the  oxyhydrogen  flame. 

The  form  of  platinum  known  as  "spongy  platinum" 
is  obtained  by  igniting  the  compound  ammonium  platinic 
chloride  as  noted  above ;  and  "  platinum  black  "  is  a  soft 
black  powder  which  results  from  the  precipitation  of 
platinum  solutions  by  means  of  reducing  agents.  In  both 
of  these  forms,  the  metal  exhibits  the  property  of  condens- 
ing gases  on  its  surface  in  a  high  degree,  and  a  mere 
fragment  of  the  spongy  metal  when  introduced  into  a 
mixture  of  hydrogen  and  oxygen  gases  in  the  proper  pro- 
portions, at  once  causes  its  explosion  and  formation  of 
water.  Even  when  cold,  platinum  has  the  property  of 
condensing  oxygen  on  its  surface,  and  in  the  forms  already 
described  and  in  that  of  gauze,  the  metal  is  used  as  a 
catalyst — for  example,  in  the  combustion  of  ammonia  to 
nitrogen  oxides  and  nitric  acid.  This  catalytic  action  is 
easily  interfered  with  by  traces  of  many  substances,  phos- 
phine  being  one  of  such  "  poisons,"  as  they  are  termed. 

Platinum  alloys  with  many  metals  and  the  introduction  of 
10  per  cent,  iridium  produces  a  combination  which  is  even 
more  resistant  to  chemical  action  than  the  pure  metal. 

There  are  two  oxides  insoluble  in  water — viz.,  the 
platinous  and  the  platinic  (PtO  and  PtO2),  both  blackish 
powders,  and  corresponding  hydroxides  (Pt(HO)2  and 
Pt(HO)4),  the  latter  of  which  when  dried  and  heated 
sufficiently,  is  decomposed,  leaving  the  metal  in  the  free  state. 

There  are  two  chlorides  (viz.,  PtCl2  and  PtCl4),  the  first 
of  which  is  a  green  powder  insoluble  in  water,  whilst  the 
latter  (obtained  by  dissolving  platinum  in  aqua  regia) 
is  a  yellowish-red  crystalline  salt  soluble  in  water.  The 
former  compound  is  used  to  some  extent  in  the  platinotype 
photographic  process. 

Two  sulphides  (PtS  and  PtS2)  are  known,  both  of  which 
are  black  and  insoluble  in  water. 

Platinous  chloride  combines  with  some  other  chlorides  to 
form  compound  salts,  such  as  potassium  platinous  chloride 
(2KCl,PtCl2)  and  ammonium  platinous  chloride  (2NH4C1, 
PtCl8),  which  is  used  in  photography ;  and  the  cyanide 


PLATINUM  385 

PLATINUM  (Continued)— 

(Pt(CN)2)  combines  with  other  cyanides  to  form  double 
compounds  known  as  platino-cyanides — for  example,  potas- 
sium platino-cyanide  (2KCN,Pt(CN)2). 

In  combination  with  ammonia,  platinous  chloride  forms 
several  remarkable  compounds  known  as  ammoniacal  pla- 
tinum bases  or  platinamines,  which  behave  as  bases  and 
form  a  corresponding  series  of  salts.  They  may  be  regarded 
as  ammonia  in  which  hydrogen  is  partly  replaced  by  a 
platinum  compound,  one  of  these  compounds  having  the 
composition  2NH2,PtCl2. 

In  chemical  industry,  platinum  is  largely  used  as  a  cata- 
lyst, also  for  making  stills  for  the  concentration  of  sulphuric 
acid,  and  in  the  electro-chemical  industry,  and  in  jewellery. 

An  alloy  used  by  jewellers,  consists  of  i  part  platinum, 
i  part  copper,  and  2  to  5  parts  silver. 

"  Platinor  "  consists  of  2  parts  platinum,  5  parts  copper, 
i  part  silver,  and  i  part  nickel. 

One  form  of  so-called  "  mockgold  "  consists  of  7  parts 
platinum  and  16  parts  copper. 

Platinum  bronze  is  made  of  i  part  platinum,  90  parts 
nickel,  and  9  parts  tin  ;  whilst  one  variety  of  dentist's  alloy  is 
made  of  5  parts  platinum,  3  parts  gold,  and  4  parts  palladium. 

In  the  forms  of  crucibles,  dishes,  foil,  spatulas,  weights, 
wire,  etc.,  it  is  largely  used  in  laboratories  on  account  of 
its  refractory  nature — that  is,  its  capability  of  withstand- 
ing exposure  to  a  high  degree  of  heat  without  damage  or 
attack  by  many  chemicals.  It  can  only  be  dissolved  by 
nitrohydrochloric  acid  (aqua  regia).  Care  has  to  be  taken, 
however,  that  it  is  not  exposed  to  the  action  of  other 
molten  metals  such  as  lead,  as  the  two  metals  will  form  an 
alloy  if  exposed  to  a  sufficiently  higbftemperature,  and  result 
in  the  ruin  of  the  platinum,  which  is  a  very  costly  metal. 

In  the  form  of  foil,  as  held  by  a  pair  of  tongs  in  the 
hands,  it  is  very  useful  for  testing  the  action  of  heat  upon 
chemical  substances  placed  on  its  surface,  the  foil  being 
placed  directly  over  the  flame  of  a  spirit-lamp  or  Bunsen 
burner.  It  can  thus  be  ascertained  whether  the  substance 
fuses  or  chars  (indicating  the  presence  of  organic  matter), 
or  is  volatile,  or  gives  off  a  distinctive  smoke  or  odour  ;  and 
if  it  burns,  whether  it  does  so  with  any  notable  feature  or 
communicates  any  particular  colour  to  the  flame  to  which  it 
may  be  exposed,  and  so  forth. 

Platinum  Crucibles  are  most  useful  for  exposing  sub- 
stances to  heat  with  the  view  of  burning  off  volatile  or 
organic  constituents,  or  of  fusing  refractory  substances  with 

25 


386 


PLATINUM— PNEUMATIC  TROUGH 


PLATINUM  (Continued)— 

added  chemicals  (fluxes)  in  order  to  obtain  them  in  a  form 
soluble  in  some  menstruum. 

Platinum  Dishes  are  utilized  for  evaporation  of  solutions 
which  are  likely  to  attack  glass  or  porcelain. 

Platinum  Weights  of  small  size  are  valuable  because 
the  metal  does  not  tarnish  in  the  air,  and  the  weights  are 
not  easily  corroded  by  accidental  contact  with  chemicals  as 
are  copper  and  brass  weights ;  0-5  gramme,  0-2  gramme, 
o-i  gramme,  and  some  smaller  ones,  are  among  those  fre- 
quently employed. 

Platinum  Wire  is  useful  for  stirring  liquids  which  attack 
glass  rods,  and  for  exposing  liquids  or  solids  spread  over  its 
surface  to  the  flame  of  a  Bunsen  burner,  in  order  to  note 
the  distinctive  features  attendant  thereon.  For  this  applica- 
tion the  wire  is  bent  into  a  loop  at  one  end,  so  that  a  bead 
of  the  liquid  or  solid  to  be  tested  may  be  held  thereon,  the 
other  end  of  the  wire  being  held  by  tongs,  or  fixed  in  a 
wooden  handle,  or  fused  into  a  glass  tube.  (See  Borax,  p.  65.) 

PLATINUM  BASES  (Organic) — Combination  of  salts  of  the 
amines,  such  as  the  chlorides,  with  platinic  chloride — for 
example,  methylamine  platinichloride  ((CH3NH3)2PtClg). 
(See  Amines,  p.  28.) 

PLATINUM  ORE— Native  platinum. 

PLUMBAGO — Another  name  for  graphite  or  black-lead.  (See 
Carbon.) 

PNEUMATIC  TROUGH— An  appliance  used  for  the  collection 
of  gases,  consisting  of  a  trough  made  of  glass  or  tinplate, 

and  provided 
with  a  shelf  as 
shown  in  figure. 
For  use  in  con- 
nection with  gases 
that  are  insoluble 
with  water,  it  is 
charged  with  that 
fluid,  so  as  to  well 
cover  the  shelf 
near  the  top.  In 
some  other  cases 
mercury  is  used, 
necessitating  the 
employment  of  a 

stoneware,  glass,  or  porcelain  bath.     The  figure  shows  the 
trough  in  connection  with  a  generator  (Woulfe's  bottle) 


PNEUMATIC  TROUGH—POLARIZATION 


387 


PNEUMATIC  TROUGH  (Continued)— 

such  as  is  used  for  making  carbon  dioxide  from  marble  and 
hydrochloric  acid,  the  end  of  the  bent  tube  being  passed  into 
the  water  in  the  trough  and  up  underneath  the  test-tube  (as 
shown)  or  other  collecting  vessel  (filled  with  water  and 
'inverted  and  placed  over  the  funnelled  hole  in  the  shelf),  in 
which  the  gas  is  to  be  stored  by  displacement  of  the  water. 

PODOPHYLLIN— A  kind  of  resin  extracted  from  the  roots  of 
Podophyllum  peltatum,  soluble  in  alcohol  and  ether,  and 
used  in  medicine. 

POISONS  AND  ANTIDOTES— 


Acids 

Aconite 
Alkalies 
Antimony 

Arsenic 


Benzene 

Petroleum 

Paraffin 

Chlorine 

Chloral 

Chloroform  / 

Carbolic  acid 


} 


Copper         \ 

Corrosive      I 

sublimate ) 

Lead  salts  .. 


Magnesia,  lime,  or  chalk  made  into  a  milk 

with  water. 

Stomach-pump  or  emetic. 
Emetic,  followed  by  dilute  vinegar. 
Emetic,  decoction  of  bark  or  strong  tea,  and 

keep  warm. 
Emetic,  followed   by  freshly  precipitated 

ferrous  oxide,  or  white-of-egg  beaten  up 

in  milk,  or  magnesia. 

Emetic,  fresh  air  and  artificial  respiration 
when  necessary. 

Magnesia.     (See  Gassing.) 

Emetic,  keep  awake  and  artificial  respira- 
tion when  necessary. 

Olive  oil,  emetic  or  stomach-pump,  fol- 
lowed by  stimulants. 

Encourage  vomiting,  then  give  eggs  beaten 
up  in  milk. 


Laudanum 

Morphia 

Opium 

Oxalic  acid. 


Sodium  sulphate  or  magnesia. 

Emetic  or  stomach-pump,  or  purified  char- 
coal-powder if  swallowed  immediately 
after  the  poisoning,  and  keep  patient 
well  awake. 

Chalk  and  water  freely. 

One  of  the  best  emetics  is  mustard — half  a  tablespoonful 
mixed  in  half  a  tumbler  of  water,  and  for  children  one  or 
two  teaspoonfuls  of  ipecacuanha  wine  every  ten  minutes. 
Another  good  emetic  for  adults  is  a  teaspoonful  of  sulphate 
of  alumina. 

POLARIZATION — Many  liquids  exhibit  optical  activity,  and 
effect  the  rotation  of  a  ray  of  polarized  light  when  placed  in 
a  column  between  two  Nicol  prisms  in  a  suitable  instrument. 


388  POLARIZATION— POPULIN 

POLARIZATION  (Continued)— 

A  Nicol  prism  composed  of  Iceland  spar — pure  crystallized 
calcium  carbonate — is  split  along  a  diagonal  plane  and 
then  cemented  together  again  with  Canada  balsam.  This 
gives  a  pencil  of  light,  the  vibrations  of  which  are  in  one  plane 
only,  and  light  so  obtained  is  said  to  be  polarized.  The  polari- 
meter  is  the  instrument  which  measures  the  angle  through 
which  the  polarized  ray  is  turned  to  the  right  or  to  the  left. 

POLLUX  (Pollucite) — A  complex  silicate  containing  caesium, 
occurring  in  pegmatite,  found  in  Maine,  etc. 

POLONIUM — A  radio-active  substance  obtained  from  pitch- 
blende, to  which  no  definite  composition  has  yet  been 
assigned. 

POLYBASITE — A  mineral  compound  sulphide  of  silver  and 
antimony,  found  in  some  of  the  United  States  of  America 
and  elsewhere. 

POLYMERISM — A  form  of  isomerism.  Substances  having 
the  same  percentage  composition  but  distinct  in  characters 
and  differing  in  formulas  as  evidenced  by  determination  of 
their  molecular  weights,  as,  for  instance,  aldehyde  (C2H4O2), 
which  slowly  changes  into  paraldehyde  (C6H12O3),  the 
last  named  being  the  polymer  and  its  molecular  weight 
being  a  multiple  of  that  of  its  originating  compound.  (See 
Isomerism.) 

POLYPEPTIDES — Hydrolized  derivatives  of  proteins  re- 
sembling peptones  in  some  respects,  and  of  which  the 
so-called  amino-acid  groups  form  conspicuous  features. 
(See  Albumins,  Enzymes,  and  Proteins.) 

POPPY  OIL  is  expressed  from  the  seeds  of  the  black  poppy 
(Papaver  somniferum,  var.  nigrum),  which  yield  about  50  to 
60  per  cent.  It  contains  about  8  per  cent,  of  solid  fatty 
acids,  30  per  cent,  oleic  acid,  60  per  cent  linoleic  acid,  and 
5  per  cent,  linolenic  acid.  It  resembles  olive  oil  in  appear- 
ance ;  its  sp.  gr.  is  0-9249,  saponification  value  193  to  195, 
iodine  value  153  to  157,  and  refractive  index  1-457;  it 
solidifies  at  —  18°  C.,  and  is  one  of  the  drying  class  of  oils. 
It  is  said  to  be  used  as  food  in  some  parts  of  Germany 
and  France,  and  for  mixing  with  light  colours  for  use  in 
painting,  after  being  bleached  in  the  sun.  It  is  odourless 
and  soluble  in  ether,  chloroform,  and  carbon  disulphide. 

POPULIN  (or  Benzoyl  Salicin)  (C10H22O8) — A  soluble  glucoside 
contained  in  the  bark,  leaves  and  root  of  the  aspen  (Populus 
tremula),  and  which  can  be  artificially  made  from  benzoyl 
chloride  (C7H5C1O)  and  salicin  (C1?H18O7).  It  yields 
salicin  and  benzoic  acid  upon  hydrolysis. 


PORCELAIN— PORPOISE  OIL  389 

PORCELAIN  and  earthenware  articles  are  made  of  clay  coated 
or  glazed  with  some  substance  that  fuses  at  a  high  tempera- 
ture, thus  giving  them  a  coating  and  at  the  same  time 
binding  the  body  of  the  material  together  in  coherent  mass. 
The  best  quality  of  China  clay  (aluminium  silicate)  is  used 
for  porcelain  goods  and  the  poorer  qualities  of  clay  for 
earthenware  articles,  the  glaze  for  the  former  being  felspar 
in  finely  powdered  form  suspended  in  water,  into  which 
mixture  they  are  dipped  before  firing.  "  Cornish  stone  " 
consists  of  approximately  equal  parts  of  felspar,  quartz, 
and  clay,  and  is  therefore  a  ready-made  material.  For 
earthenware  goods,  a  "  salt  glaze  "  is  used  and  applied  by 
introducing  salt  into  the  furnace  containing  the  ware,  in 
which  it  is  volatilized  and  decomposed  by  the  heated  sur- 
faces of  the  articles,  causing  the  formation  of  a  fusible 
silicate  on  their  surfaces. 

Articles  of  stoneware,  such  as  jars  and  drain-pipes,  are 
salt  glazed,  while  for  many  varieties  of  earthenware  easily 
fused  glazes  containing  lead  or  borax  are  used.  The  use 
of  lead  compounds  is  viewed  with  growing  disfavour  by 
reason  of  their  poisonous  effects  in  pottery  works.  For 
fine  qualities  of  ware,  such  as  Delft  and  Majolica,  the 
surfaces  are  coated  with  an  opaque  white  glaze  containing 
stannic  oxide  (SnO2). 

Some  qualities  of  ware,  such  as  flower-pots,  etc.,  are  not 
glazed,  and  this  is  true  also  of  Spanish  cooling  vessels 
(alcarazzas)  which  are  specially  made  porous  in  order  to 
maintain  a  constant,  slow  evaporation  and  consequent 
cooling  of  the  water  contained  in  them.  (See  also  Clays 
and  Refractories.) 

POROSITY — Possession  of  pores,  interstices,  or  cavities  — 
looseness  of  binding.  Animal  charcoal,  pumice  stone, 
kieselgiihr,  spongy  platinum,  and  sponge  are  examples  of 
porous  articles.  Many  porous  articles,  particularly  ordinary 
sponge,  are  absorbent  and,  in  consequence,  take  up  or 
hold  in  a  mechanical  sense,  large  quantities  of  liquids, 
which  can  in  some  cases  be  squeezed  out  by  pressure,  thus 
consolidating  the  porous  material. 

The  interstices  between  the  atoms  of  compact  solid  and 
liquid  bodies  must  be  small,  even  if  there  are  any  inter- 
stices at  all,  so  that  porosity  is  often  conspicuous  by  its 
absence — glass,  for  example,  being  highly  impermeable  to 
oxygen,  nitrogen,  and  water.  (See  Occlusion,  p.  345.) 

PORPHYRY — A  form  of  felspar. 
PORPOISE  OIL— See  Fish  Oils. 


390    PORTLAND  CEMENT— POTASSIUM  COMPOUNDS 

PORTLAND  CEMENT— See  Cement. 

PORTLAND  STONE — An  oolitic  limestone  (calcium  carbonate 
composed  of  minute  grains. 

POTASH — See  Potassium  Compounds. 
POTASH  BULBS— See  Organic  Analyses. 

POTASSIUM  (Kalium,  K)  and  its  Compounds— Atomic  weight, 
39 '»  SP-  gr-j  0*865 ;  melting-point,  62-3°  C.  Potassium 
occurs  abundantly  in  nature  at  Stassfurt,  in  Germany,  in 
the  form  of  saline  deposits  of  various  compositions — viz., 
as  chloride  (KC1)  in  sylvinite  (sylvine),  as  a  double  chloride 
of  potassium  and  magnesium  (KCl.MgCl26H2O)  in  car- 
nallite,  and  as  a  compound  sulphate  and  chloride  (K2SO4. 
MgSO4.MgCl26H2O)  in  kainite. 

There  are  similar  and  even  richer  deposits  in  Alsace 
(mostly  pure  sylvinite)  estimated  as  sufficient  for  furnishing 
more  than  300,000,000  tons  of  potassium  oxide  (K2O).  In 
the  Italian  colony  of  Erythrea,  considerable  deposits  have 
been  found  and  worked  during  the  recent  war. 

Potassium  is  found  in  the  soil  as  a  product  of  decom- 
position of  certain  rocks  (for  instance,  felspar)  from  which 
it  finds  its  way  into  vegetable  life,  and  so  into  the  bodies 
of  the  animals  that  feed  upon  it.  This  accounts  for  the 
presence  of  potash  in  the  suint  or  fat  that  is  extracted  from 
sheep's  'wool. 

Potash  is  now  being  recovered  in  this  country  from  the 
flue  gases  and  dust  of  iron  blast-furnaces,  and  the  industry 
is  likely  to  attain  considerable  proportions.  Blast-furnace 
gas  contains  from  4  to  6  grammes  solid  particles  per  cubic 
metre,  which  yield  about  27  per  cent,  of  potassium 
chloride.  Common  salt  is  introduced  with  the  blast  charge, 
and  this,  combining  with  the  potassium  contained  in  the 
iron  ores,  forms  potassium  chloride,  which  volatilizes  and 
is  recovered  from  the  fume  and  dust. 

There  is  also  a  process  for  recovering  it  as  sulphate  from 
the  gases  and  dust  carried  over  in  the  stack  gases  of  cement 
works,  about  2  to  7  Ibs.  being  obtained  per  barrel  of  cement 
produced. 

In  the  form  of  nitrate  (KNO3)  potassium  is  found  in 
association  with  sodium  nitrate  in  the  nitrate  deposits  of 
Chili  and  Peru. 

The  metal  potassium  is  silver-white,  lustrous  and  soft. 
It  rapidly  oxidizes  in  the  air,  its  vapour  taking  fire,  so 
that  in  the  metallic  state  it  has  to  be  preserved  in  naphtha 
or  kerosine. 


POTASSIUM  COMPOUNDS  391 

POTASSIUM  (Continued)— 

Potassium  was  formerly  obtained  by  heating  a  mixture 
of  potassium  hydroxide  (KHO)  and  carbon,  the  metal  thus 
set  free  distilling  over  and  being  collected  in  naphtha,  but 
it  was  a  difficult  process  and  has  been  superseded  by 
another  in  which  the  fused  potassium  hydroxide  is  sub- 
jected to  electrolysis,  oxygen,  hydrogen,  and  potassium 
being  all  set  free.  The  potassium  floats  to  the  surface  of 
the  fused  mass  and  is  withdrawn  from  time  to  time  under 
special  precautions,  whilst  hydrogen  gas  is  given  off  at  the 
cathode  and  oxygen  at  the  anode. 

In  common  with  sodium,  it  decomposes  water,  hydrogen 
being  liberated  as  follows  : 

H20  +  K2=K20  +  H2. 

Potassium  oxide  (K2O)  can  be  obtained  as  a  grey  crys- 
talline body  of  specific  gravity  2*32,  and  when  dissolved  in 
wate-  it  forms  a  solution  of  potassium  hydrate  (hydroxide), 
or  caistic  potash,  as  it  is  also  called  : 


—  i.e,  a  combination  of  potassium  oxide  and  water, 

Tvo  other  oxides  are  known—  viz.,  the  dioxide  (K2O2) 
and  :he  tetroxide  (K2O4)  —  but  they  are  comparatively  un- 
important substances. 

Pctassium  Chlorate  (KC1O3)  is  a  crystalline  body,  soluble 
in  witer,  which  is  manufactured  on  a  considerable  scale  — 
chiely  by  the  electrolysis  of  potassium  chloride  in  a  state 
of  s«lution,  the  potassium  hydroxide  and  chlorine  thus 
procuced  being  allowed  to  mix  at  a  temperature  of  70°  C., 
thus  producing  the  chlorate,  which  can  be  obtained  from 
the  iolution  by  evaporation  and  crystallization. 

Rtassium  chlorate  is  largely  used  in  the  preparation  or 
exposives,  matches,  and  fireworks.  It  melts  at  above 
36^  C.,  and  at  380°  C.  begins  to  give  off  oxygen.  (See 
Chorine,  p.  112.) 

Jotassium  Carbonate  (K2CO3)  was  originally  obtained 
frcn  the  ashes  of  wood  —  hence  the  name  "  pot  ashes," 
ani  is  still  extracted  from  this  source  in  some  parts  of 
Canada  and  the  United  States  of  America,  where  timber  is 
atundant.  It  is  soluble  in  water  and  used  in  the  manu- 
facture of  soft  soaps,  glass-manufacture,  and  wool-washing. 

In  the  anhydrous  form  it  is  very  deliquescent,  and  it 
fcrms  a  crystalline  salt  with  water  (K2CO33H2O);  there 
i<  also  a  potassium  hydrogen  carbonate  or  so-called  bi- 
arbonate  (KHCO3),  used  in  making  baking-powders. 


392  POTASSIUM  COMPOUNDS 

POTASSIUM  (Continued)— 

Potassium  Cyanide  (KCN)  is,  a  white,  deliquescent,  soluble, 
crystalline  salt  of  very  poisonous  character  largely  used 
as  a  solvent  of  gold  in  certain  methods  of  extracting  that 
metal  from  its  natural  sources*  (See  Cyanogen,  p.  149,  and 
Gold,  p.  233.) 

Caustic  Potash  (KHO)  is  prepared  by  the  action  of  slaked 
lime  or  milk  of  lime  (CaH2O2)  upon  potassium  carbonate, 
when  calcium  carbonate  is  precipitated  and  potash  passes 
into  solution,  as  shown  by  the  equation — 

K2C03  +  CaH202  =  CaC03  +  2KHO.     / 

The  solution  is  concentrated  by  evaporation  first  of  all  in 
iron  vessels,  and  finally  to  dryness  and  fusion  in  silver  vessels. 
It  is,  however,  for  the  most  part  now  manufactured  by  an 


electrolytic  method  from  potassium  chloride.     It 


is  a  very 


deliquescent  and  caustic  substance,  and  when  dissolved  in 
water,  great  heat  is  developed. 

It  is  made  of  various  strengths,  and  extensively  used  in 
the  manufacture  of  soft  soaps. 

Potassium  Nitrate  or  Nitre  (KNO3),  also  knowiias  salt- 
petre, is  largely  used  as  a  fertilizer,  for  picklir*  meatj 
in  the  manufacture  of  gunpowder,  and  in  pyrotech  ' 


is  a  white,  crystalline  salt,  readily  soluble  in  wate 


ics.     It 
,  and  is 

for i the  most  part  obtained  from  Chili  nitre  by  steaniheating 
a  solution  of  it  in  admixture  with  one  of  potassiumchloride 


(KC1),  when  a  double  decomposition  occurs,  expr 
follows  : 

NaNO3  +  KCl=KN03 

Under  the  working  conditions  of  the  process,  mo 


ssed  as 


of  the 


NaCl  is  precipitated  in  a  crystallized  form  and  removed, 
and  the  KNO3  is  obtained  later  by  crystallization  of  the 
mother-liquor  and  purified  by  recrystallization. 

Potassium  Chloride,  Bromide,  and  Iodide  (KC1,  Kir,  and 
KI)  are  all  white,  crystalline  salts  readily  soluble  inwater. 
The  chloride  is  used  as  a  fertilizer ;  the  bromide  is  ised  in 
photography  and  medicine,  and  the  iodide  is  a  vauable 
medicinal  agent. 

Potassium  Fluoride  (KF)  forms  a  white,  deliquscent 
hydrate  with  water  (KF.2H2O),  and  finds  some  ue  in 
etching  glass. 

Potassium  Sulphides  include  K2S,  K2S2,  K2S3,  and  I2S5, 


POTASSIUM  COMPOUNDS  393 

POTASSIUM  (Continued)- 

all  of  which  are  soluble  in  water,  and  are  decomposed  by 
acids,  evolving  hydrogen  sulphide  (H2S). 

Potassium  Sulphates — The  sulphate  and  bisulphate 
(K2SO4  and  KHSO4),  are  both  colourless  and  crystalline, 
and  to  some  extent  soluble  in  water,  although  not  so 
soluble  as  most  of  the  other  potassium  compounds.  The 
ordinary  sulphate,  which  melts  at  1,072°  C.,  is  used  in  glass- 
manufacture,  as  a  fertilizer,  and  in  the  preparation  of  alums, 
whilst  the  bisulphate  is  used  as  a  flux. 

Potassium  Sulphite  (K2SO3)  and  potassium  hydrogen 
sulphite  or  acid  potassium  sulphite  (KHSO3)  are  crys- 
talline salts  soluble  in  water,  both  of  which  (and  particu- 
larly the  latter)  are  used  in  the  brewing  industry  and  as 
sources  of  sulphur  dioxide. 

Potassium  Manganate  and  Permanganate  —  See  Man- 
ganese, p.  306. 

Potassium  Acetate  (K(C2H3O2)) — A  white,  crystalline 
powder,  soluble  in  water,  used  in  medicine,  etc. 

Potassium  Phosphate  (KH2PO4) — A  colourless,  crystal- 
line salt  used  in  compounding  baking  powders  and  in 
medicine. 

Potassium-Sodium  Tartrate  (Rochelle  Salt)  (KNa(C4H4O6), 
4H2O) — A  colourless,  crystalline  salt  which  loses  its  water 
at  215°  C.  Used  as  a  depilatory  and  in  medicine. 

Potassium  Sulphocyanate  (KCNS) — A  colourless,  crystal- 
line compound  used  in  making  freezing  mixtures  and 
making  artificial  mustard  oil. 

Potassium  Oxalate  (K2C2O4H2O)  is  a  colourless,  crystal- 
line salt  soluble  in  water  ;  so  also  is  the  potassium,  hydro- 
gen oxalate  (KHC2O4,H2O)  (sometimes  called  binoxalate) 
and  the  acid  potassium  oxalate  (KHC2O4,C2H2O4,2H2O) 
(also  known  as  quadroxalate). 

Potassium  Bitartrate  (KHC4H4O6)  is  a  white,  crystal- 
line, soluble  salt,-  used  in  compounding  baking-powders. 
(See  Tartar.) 

Potassium  Chromate  and  Bichromate .  (See  Chromium, 
P-  "5-) 

Prussiate  of  Potash  (Red)  or  Potassium  Ferricyanide 
(K3Fe(CN6)) — A  crystalline,  poisonous  substance  of  blood- 
red  colour,  readily  soluble  in  water,  which  forms  with 
solutions  of  many  of  the  heavy  metals,  precipitates  of 
characteristic  colours  ;  hence  its  use  in  dyeing  and  calico- 
printing  when  used  alone,  or  with  solutions  of  iron  salts 


394         POTASSIUM  COMPOUNDS— PRINTING  INK 

POTASSIUM  (Continued)— 

for  the  production  of  blue  colours  on  wool  and  cotton. 
It  is  also  used  in  connection  with  the  discharge  of  indigo- 
blue  colouring  from  calico  and  the  preparation  of  some 
pigments.  It  is  made  by  the  action  of  chlorine  upon  the 
yellow  prussiate  of  potash. 

Prussiate  of  Potash  (Yellow)  or  Potassium  Ferrocyanide 
(K4Fe(CN6))  is  a  crystalline  substance  of  lemon-yellow 
colour,  readily  soluble  in  water  but  is  not  poisonous.  It  is 
made  by  heating  a  mixture  of  nitrogenous  material  such  as 
dried  blood,  horn  and  parings  of  hides,  with  an  equal 
weight  of  potassium  carbonate  and  one-third  of  their  weight 
of  iron  filings.  There  is  also  a  process  of  making  it  from 
the  "  spent  oxide  "  from  gasworks  which  contains  cyanogen 
compounds.  Like  the  red  prussiate,  it  is  manufactured 
on  a  large  scale  for  use  in  dyeing  and  calico-printing,  also 
in  the  preparation  of  Prussian  blue  and  in  processes  of 
electro-plating  and  electro-gilding. 

POTATO  SPIRIT— See  Fusel  Oil. 
POTTERY— See  Porcelain. 

PRASEODYMIUM  (Pr) — Atomic  weight,  140-9 ;  sp.  gr.  6-4754. 
A  little  known  and  extremely  rare  element  of  the  cerium 
group  occurring  in  the  earth  didymia  and  monazite  sand. 
It  has  been  isolated  by  the  electrolysis  of  its  anhydrous 
chloride.  It  decomposes  water,  melts  at  940°  C.,  and  gives 
two  oxides,  one  of  greenish-white  colour  (Pr2O3),  and 
another  which  is  nearly  black  (Pr4O7).  The  salts,  including 
a  chloride  (PrCl3,7H2O)  and  a  sulphate  (Pr(SO4)3,8H2O), 
are  green  in  colour. 

PRECIPITATE— To  deposit  or  fall  in  the  solid  state  out  of  a 
solution.  For  example,  when  a  solution  of  sodium  chloride 
is  added  to  one  of  silver  nitrate,  the  following  interaction 
takes  place : 

NaCl  +  AgN03  =  NaN03  *  AgCl, 

and  the  silver  chloride,  being  insoluble,  is  thrown  out  of 
solution  as  a  white  precipitate. 

PREMIER  JUS— The  oily  fat  expressed  from  beef-fat  at  48°  C. 
through  filter-cloths. 

PRIMULIN— See  Dyes. 

PRINTER'S  IRON  LIQUOR— Ferrous  acetate  (FefC2H3O2)2) ; 
used  as  a  mordant  in  dyeing. 

PRINTING  INK— See  Inks. 


PRODUCER  GAS— PROTEINS  395 

PRODUCER  GAS  is  made  by  passing  air  over  red-hot  coke  or 
coal,  thus  generating  a  mixture  of  carbon  dioxide  (CO2)  and 
carbon  monoxide  (CO)  with  the  nitrogen  contained  in  the 
air  used.  It  contains  about  30  per  cent,  of  carbon  monoxide 
and  is  largely  used  for  many  purposes  on  account  of  its 
cheapness.  (See  Gas,  p.  216,  and  Nickel,  p.  330.) 

"PROMETAL" — A  variety  of  cast  iron  specially  applicable  to 
the  construction  of  furnace  parts. 

PROOF-SPIRIT — Alcohol  containing  49-28  per  cent,  real 
alcohol  by  weight,  and  57  -10  per  cent,  by  volume,  having 
a  sp.  gr.  of  0-920  ;  every  additional  0-5  per  cent,  alcohol 
above  that  is  described  as  "  i  degree  over  proof."  The 
factor  for  calculating  proof-spirit  from  volume  percentage 
is  1-7535- 

PROPANE — See  Hydrocarbons. 

PROPIONIC  ACID  (C3H6O2)— One  of  the  normal  fatty  acids 
of  small  importance  as  a  natural  product,  said  to  be  con- 
tained in  the  products  of  wood  distillation,  also  in  cocoa-nut 
milk  when  turned  sour  and  in  crude  oil  of  amber.  It  is 
a  colourless,  oily  acid,  which  boils  at  140-7°  C.,  has  a 
sp.  gr.  0*987,  is  soluble  in  water  and  alcohol,  with  an  odour 
something  like  that  of  acetic  acid. 

PROPYL  ALCOHOL— See  Alcohols. 
PROPYLAMINE— See  Amines. 

"  PROTARGOL  " — A  protein  compound  of  silver  used  as  an 
antiseptic  and  in  medicine. 

PROTEINS — The  name  given  by  chemists  to  a  great  variety 
of  colloidal  nitrogenous  bodies  of  animal  and  vegetable 
origin  and  albuminous  character  like  egg  albumin  and  blood 
albumin,  globulins  (such  as  fibrin  and  globulin  from  the 
lens  of  the  eye),  and  gluteins  (of  vegetable  origin,  etc.); 
but  which,  while  admitting  of  some  rough  classification 
according  to  their  varying  properties,  are  all  collectively 
grouped  as  albuminoids.  Many  of  these  complicated  com- 
pounds, when  in  solution,  are  coagulated  by  heat,  and 
when  subjected  to  hydrolysis  they  yield  the  so-called 
albumoses,  polypeptides,  peptones,  ammonia,  and  ultimately 
amino-acids,  including  glycine,  leucine,  tyrosine,  aspartic 
acid,  etc. 

Dry  yeast  contains  about  50  per  cent,  of  proteins,  and  is 
used  in  the  preparation  of  a  food  product  resembling  ex- 
tract of  meat  named  "  marmite."  (See  Albumins,  Enzymes, 
and  Foods.) 


396  PROTOCATECHUIC  ACID—PUCHERITE 

PROTOCATECHTJIC  ACID  (C7H6O4  or  C6H3(OH)2CO,OH)— 
A  crystalline  substance  soluble  in  water,  made  by  heating 
catechol  (C6H4(OH)2)  with  ammonium  carbonate. 

PROTOPLASM— See  Bioplasm. 

PBOTYLE  (Primordial  Substance) — The  hypothetical  ultimate 
form  of  matter  of  which,  conceivably,  the  various  elements 
are  constituted,  and  to  which  they  may  in  that  case  be  re- 
ducible. The  current  opinion  is  that  the  so-called  elements 
are  not  absolutely  elemental  in  character,  and  really  con- 
sist of  the  same  primordial  substance,  but  differing  in 
properties  according  to  their  structure  and  the  varying 
conditions  under  which  they  are  revealed.  (See  Atoms, 
Elements,  and  Matter.) 

PROUSTITE— A  mineral  double  sulphide  of  silver  and  arsenic 
(3Ag2S.As2S3)  found  in  Arizona,  New  Mexico,  etc. 

PRUSSIAN  BLUE  (Ferric  Ferrocyanide)  (Fe4(Fe(CN)6)3)— The 
name  of  a  blue  pigment  (compound  of  iron  and  cyanogen) 
made  from  potassium  ferrocyanide  and  ferric  salts,  used  in 
dyeing  and  making  inks  and  paints.  There  are  various 
formulae  for  making  the  several  varieties  of  Prussian  blue 
(Chinese  and  bronze  blues),  but  they  may  be  stated  to  be 
based  generally,  upon  the  action  of  potassium  chlorate  and 
sulphuric  acid  on  a  mixture  of  potassium  ferrocyanide  and 
ferrous  sulphate  in  hot  solution. 

Turnbull's  Blue  (ferrous  ferricyanide)  is  Fe3(Fe(CN)6)2. 

PRUSSIAN  GREEN  is  prepared  by  the  long-continued  action 
of  chlorine  upon  potassium  ferrocyanide. 

PRUSSIC  ACID — A  common  name  for  hydrocyanic  acid  (HCN). 
(See  Hydrocyanic  Acid.) 

PTOMAINES — The  name  given  to  certain  chemical  compounds 
resulting  from  the  action  of  micro-organic  life  in  the  process 
of  putrefaction.  They  are  of  a  nitrogenous  basic  nature — 
possibly  alkaloidal — and  very  poisonous.  Several  of  these 
substances  have  been  isolated,  including  a  complicated 
animated  body  named  "  putrescine "  (tetramethylene  di- 
amine)  and  another  named  "  cadaverine  "  (pentamethylene 
diamine). 

PTYALIN — The  active  principle  of  saliva  which  by  its  action 
on  starchy  food  converts  the  starch  into  sugar,  thus  behav- 
ing as  an  enzyme.  It  is  present  in  saliva  to  the  extent  of 
about  ij  parts  per  1,000,  and  is  most  active  at  40°  C. 
(See  Enzymes.) 

PUCHERITE  (BiVO4) — A  rare  mineral  vanadium  compound 
of  bismuth. 


PULEGONE—PURPURIN  397 

PULEGONE  (C10H16O)— A  constituent  of  some  essential  oils 
(including  pennyroyal  oil)  in  the  nature  of  a  ketone, 
isomeric  with  ordinary  camphor.  It  gives  a  hydrochloride, 
C10H17OC1. 

PUMICE-STONE — A  porous  lava  of  volcanic  production,  prob- 
ably derived  from  felspar,  which  floats  in  water,  and  is  com- 
posed largely  of  silicate  of  aluminium.  In  a  finely  powdered 
state  it  is  used  as  an  abrasive  and  as  a  base  for  carrying 
catalysts.  The  seat  of  the  Italian  pumice  industry  is  the 
volcanic  island  of  Lipari. 

PUMILINE — The  essential  oil  from  the  leaves  of  Pinus  piimilio 
(coniferae),  used  for  inhalations. 

PUMPS  (EXHAUST)— Contrivances  for  reducing  the  pressure 
within  vessels  and  thereby  creating  more  or  less  vacuity. 
One  such  apparatus  is  known  as  the  filter  or  water  pump, 
in  which  a  jet  of  water  under  pressure  escapes  in  such  a 
way  as  to  cause  air  to  be  drawn  by  suction  from  the  space 
to  be  exhausted. 

The  "  Sprengel "  pump  is  an  appliance  in  which  mercury 
is  used  instead  of  water,  and  by  its  means  the  pressure  may 
be  reduced  to  o'ooi  mm.  of  mercury. 

The  "Topler"  mercury  pump  is  even  more  effective, 
giving  a  vacuity  of  o'ooooi  mm.  of  mercury,  and  when 
coupled  with  the  use  of  charcoal  to  assist  in  the  absorp- 
tion of  any  remaining  gas  in  the  vessels  to  be  exhausted,  an 
enormously  enhanced  result  is  attained.  Even  greater 
claims  are  made  on  behalf  of  the  Gaede  pistonless  pump ; 
but  the  greatest  degree  of  exhaustion  is  said  to  be  realized 
by  an  arrangement  in  which  liquid  air  and  charcoal  are 
used  in  association. 

PURPLE  OP  CASSIUS — A  purple  -  coloured  body  obtained  in 
the  form  of  an  impalpable  precipitate  by  adding  a  solution 
of  tin  chloride  (SnCl2)  to  a  solution  of  gold,  or  by  adding 
a  neutral  solution  of  gold  chloride  to  one  of  the  mixed 
stannous  and  stannic  chlorides.  A  purple  of  fine  tint  is 
produced  when  the  tin  chloride  is  first  of  all  added  to  a 
solution  of  ferric  chloride  until  a  shade  of  green  is  obtained 
and  then  adding  this  mixture  very  gradually  to  a  solution 
of  gold  chloride  (AuCl3).  The  precipitate,  when  collected 
and  dried,  forms  the  so-called  purple  or  powder  of  cassius, 
which  is  used  as  a  colouring  material  in  the  red  glass  of 
Bohemia. 

PURPURIN  (C14H8O5) — A  red  colouring  matter,  being  a 
valuable  dye  extracted  from  madder  by  the  same  process 


398  PURPURIN—PYRIDINE 

PURPURIN  (Continued)— 

as  alizarin  and  separated  therefrom  by  its  greater  solubility 
in  alum  liquor.  From  strong  alcohol  it  crystallizes  in  red 
needles.  It  is  more  soluble  in  water  than  alizarin  and  is 
produced  synthetically  from  anthracene. 

PUS — Creamy  matter  resulting  from  inflammation  of  wounds, 
and  found  in  abscesses,  consisting  of  serum  and  degraded 
tissue,  crowded  with  white  corpuscles  (leucocytes)  which 
have  undergone  degenerative  change,  and  generally  accom- 
panied with  abundant  micrococci  and  bacteria.  It  is  very 
subject  to  infection  or  putrefaction,  thus  leading  to  the 
production  of  some  of  the  products  associated  with  the 
hydrolysis  of  albuminoid  matters.  (See  Ptomaines.) 

PUTREFACTION  —  The  expression  by  which  is  indicated  a 
number  of  chemical  changes  in  animal  and  vegetable  com- 
pounds, which  are  in  the  nature  of  hydrolysis  and  oxidation 
initiated  by  microbes.  (See  Bacteria,  Microbes,  Ptomaines.) 

PUTTY — A  mixture  of  whiting  (calcium  carbonate)  and  18  per 
cent,  linseed  oil,  with  or  without  added  white-lead. 

PUTTY  POWDER — Impure  stannic  oxide,  containing  about 
25  to  50  per  cent,  of  that  substance,  with  from  71  to  46  per 
cent,  of  lead  oxide,  and  4  per  cent,  of  impurities ;  used  in 
enamelling  and  for  polishing.  (See  Tin.) 

PYRARGYRITE— A  native  compound  of  antimony  and  silver 
sulphides  (Ag3SbS3),  mined  in  the  United  States  of 
America  and  New  Mexico. 

PYRENE  (C16H10) — A  crystalline  hydrocarbon  accompanying 
chrysene,etc.,  contained  in  the  distillate  from  coal  tar  coming 
over  above  360°  C.  It  melts  at  149°  C. 

PYRETOL— The  active  principle  of  Insect  Powder  —  very 
poisonous  to  cold-blooded  animals.  (See  Insect  Powder.) 

PYRIDINE  (C5H5N  or  CH(CH.CH)2N)— A  practically  colour- 
less, liquid,  basic  substance  of  penetrating,  sharp  odour, 
contained  in  tar  and  bone  oil,  and  present  also  in  tobacco 
smoke.  It  has  a  sp.  gr.  of  0-9746,  boils  at  115°  C,  and  is 
soluble  in  water,  alcohol,  ether,  benzol,  etc.  It  can  be 
extracted  in  association  with  some  of  its  homologues  from 
the  lower-boiling  fractions  of  tar  distillates  by  agitation 
with  sulphuric  acid,  in  which  they  dissolve,  and  in  a  pure 
state  by  heating  its  carboxylic  acid  with  lime. 

It  is  used  to  some  extent  as  a  remedy  for  asthma,  also  as 
a  denaturant  for  alcohol,  and  is  a  valuable  solvent  used  in 
the  rubber,  paint,  and  other  industries. 
Chemically,  it  has  a  ring  constitution  similar  to  benzene. 


PYRITES— PYROLU  SITE  399 

PYRITES — The  mineralogical  name  of  a  number  of  natural 
compounds  consisting  of  sulphides  (chiefly  iron  and  copper). 
There  is  a  large  consumption  of  pyrites  in  this  country  in 
connection  with  the  manufacture  of  sulphuric  acid,  imports 
coming  from  Spain,  Portugal,  Norway,  and  other  parts,  in 
addition  to  that  which  is  mined  in  Ireland  and  Cornwall. 
Iron  pyrites  (FeS2)  exist  in  many  countries  and  in  several 
varieties.  A  large  proportion  of  pyrites  is  so-called  cuprous 
pyrites  (Cu2S,Fe2S3).  Many  others  are  of  arsenical  char- 
acter. One  of  the  arsenical  pyrites  is  named  mispickel  and 
has  the  composition  FeAs2,FeS2 ;  others  contain  a  notable 
quantity  of  nickel. 

The  silver  and  copper  contained  in  pyrites  used  in  the 
sulphuric  acid  manufacture  are  recovered  from  the  burnt 
ore  by  chemical  processes.  The  Rio  Tinto  iron  pyrites 
contains  about  50  per  cent,  sulphur,  40  per  cent,  iron,  from 
1-5  to  3-80  per  cent,  copper  and  i  oz.  4  dwts.  of  silver  per 
ton;  the  Tharsis  pyrites  about  3-5  per  cent,  copper  and 
15  dwts.  silver;  and  the  San  Domingo  (Mason's)  about 
370  per  cent,  copper  and  15  dwts.  of  silver.  In  the  re- 
covery of  the  copper,  great  care  has  to  be  taken  to  first  of  all 
get  rid  of  the  arsenical  constituent.  (See  Copper  and  Iron.) 

PYROCATECHIN.— See  Catechol. 

PYROGALLIC  ACID  or  PYROGALLOL  (C6H6O3  or 
C6H3(OH)3)  can  be  obtained  from  gall  nuts,  but  is  best 
obtained  by  heating  gallic  acid  (C7H6O5)  with  water  in  an 
autoclave,  thus  causing  the  elimination  of  carbon  dioxide. 
It  is  a  white  crystalline  substance  which  melts  at  132  '5°  C. 
and  can  be  sublimed  without  decomposition ;  is  soluble  in 
water,  and  is  a  very  powerful  reducing  agent  for  silver 
salts,  which  gives  it  a  use  in  photography  as  a  developer. 
Dissolved  in  alkali,  it  has  a  great  affinity  for  oxygen  (see 
Nitrogen,  p.  333,  and  Organic  Analyses,  p.  354),  and  so  is 
much  used  in  gas  analysis.  With  a  solution  of  a  ferrous 
salt  it  produces  a  beautiful  indigo  colour.  Commercial 
samples  exhibit  a  melting-point  of  from  125°  to  132°  C. 

PYROLIGNEOUS  ACID— The  crude  acetic  acid  liquor  obtained 
by  the  dry  distillation  of  wood.  The  acid  distillate  is 
neutralized  by  lime  and  the  calcium  acetate  thus  obtained 
is  distilled  with  hydrochloric  acid,  thus  yielding  the  acetic 
acid  as  distillate. 

PYROLUSITE — The  most  abundant  manganese  ore  and  one 
of  the  richest  in  its  oxygen  content,  containing  from  80  to 
87  per  cent,  of  red  manganese  oxide,  and  10  to  14  per  cent. 
of  oxygen.  It  is  imported  chiefly  from  Spain  and  is  largely 


400  PYROLUSITE— PYROXYLIN 

PYROLUSITE  (Continued)— 

used  in  the  manufacture  of  chlorine,  although  not  to  the 
same  extent  as  in  the  days  before  the  Weldon  process  was 
introduced  for  the  regeneration  of  manganese  from  the  waste 
liquors.  (See  Chlorine  and  Weldon  Chlorine  Process.) 

PYROMETERS — Instruments  for  determining  high  tempera- 
tures, such  as  those  of  furnaces  and  the  fusing-points  of 
metals.  They  are  of  various  classes,  including  the 
"  contact  "  or  "  immersion  "  type,  being  so  called  because 
one  part  of  the  pyrometer  is  immersed  in  the  heated 
material ;  and  the  "  distance"  type,  in  which  no  such  part 
is  immersed.  The  mercury  thermometer  is  a  simple  form 
of  the  first-named  class,  and  can  be  applied  in  respect  of 
temperatures  up  to  500°  C. 

The  thermo-electric  pyrometer  consists  of  two  dissimilar 
metals  in  wire  form,  at  the  tip  of  which  is  a  rod  enclosed 
in  a  protecting  tube,  and  this  receives  the  heat  and  is 
termed  the  "  hot  junction,"  while  the  other  ends  of  the  two 
wires  are  outside  the  source  of  heat  ("cold  junction"). 
The  temperature  registered  on  an  indicator  is  the  difference 
between  that  of  the  two  junctions.  Many  combinations 
of  metals  are  available.  Nickel  chromium  alloys  are  stated 
to  give  the  highest  electro-motive  force  in  commercial  use, 
and  are  useful  for  temperatures  up  to  about  1,360°  C. 

PYROMORPHITE  (Green  Lead  Ore)  (3Pb3P2O8,PbCl2)— A 
natural  lead  compound  in  the  nature  of  a  chlorophosphate 
found  in  some  of  the  United  States  of  America. 

"PYRONIUM" — A  proprietary  opacifying  substitute  for  tin 
oxide  in  enamels,  3  per  cent,  of  which  and  3  per  cent,  of  tin 
oxide  giving  better  results,  it  is  claimed,  than  8  per  cent,  of 
tin  oxide  alone,  in  leadless  enamels  and  being  much  cheaper. 

PYROPHORIC  ALLOYS  (Ferrocerium)— Alloys  made  of  a 
mixture  of  rare-earth  metals  (chiefly  cerium)  with  about 
30  per  cent,  of  iron  ;  a  sparking  substance  used  in  making 
cigar  lighters  and  for  tracing  the  flight  of  shells,  the  friction 
of  the  air  generating  sufficient  heat  to  cause  a  piece  of  the 
alloy  attached  thereto,  to  burst  into  flame  and  thereby 
indicate  their  path.  The  cerium  is  obtained  from  the 
residues  of  the  gas-mantle  industry. 

PYROXYLIN  (Gun-cotton)  is  typical  of  a  number  of  substances 
used  in  competition  with  oil  products,  in  the  preparation  of 
artificial  leather  cloth  and  oil  varnishes,  and  consists  of  a 
solution  of  nitrated  cellulose  in  a  solvent  of  comparatively 


PYROXYLIN— QUICKLIME  401 

PYROXYLIN  (Continued)— 

high  boiling-point,  mixed  with  castor  oil  or  nitrated  castor 
oil  to  impart  body  and  flexibility  to  the  product.  (See 
Cellulose.) 

PYRRHOTIN  (Pyrrhotite) — Magnetic  pyrites  of  varying  com- 
position and  crystalline  character  found  in  many  districts. 

PYRROL  (C4H4NH)— A  constituent  of  bone  oil.  It  is  a  liquid 
basic  body  of  the  furane  group  soluble  in  alcohol  and  ether  ; 
sp.  gr.  0*9669  and  boiling-point  130°  C. 

QUALITATIVE  ANALYSIS  is  the  term  applied  to  the  methods 
used  for  ascertaining  the  nature  of  the  constituents  of 
substances.  (See  Reagents.) 

QUANTITATIVE  ANALYSIS  is  the  term  applied  to  the 
methods  used  for  determining  the  amount  of  each  con- 
stituent of  any  substance.  (See  Organic  Analyses  and 
Volumetric  Analyses.) 

QUARTZ — An  anhydrous  crystalline  form  of  silica.  (See Silica.) 

QUASSIA  WOOD  (Bitter  Wood)  comes  from  a  tree  (Picrana 
excelsa)  which  grows  in  Jamaica  and  the  West  Indies.  It 
contains  about  0*03  per  cent,  of  a  very  bitter  crystal- 
line substance  named  quassiin  (C32H42O10),  which  is 
soluble  in  alcohol  and  to  a  smaller  extent  in  water. 
Infusions  of  the  wood  are  used  in  medicine  and  as  a  bitter. 

QUEBRACHO  EXTRACT,  used  in  tanning  and  dyeing  as  a 
substitute  for  catechu  and  sumach,  is  obtained  from  the  wood 
of  trees  (Aspidosperma)  which  grow  abundantly  in  Brazil 
and  the  River  Plate  districts  of  Argentine  and  Paraguay. 
The  dry  extract  contains  about  65  per  cent,  tannin.  The 
production  for  1919  amounted  to  upwards  of  170,000  tons. 

QUERCITIN  (C15H10O7.2H2O) — A  brown  crystalline  substance 
of  melting-point  313°  C.,  soluble  in  alkaline  solutions  and 
used  in  dyeing.  It  is  prepared  from  quercitrin.  (See 
Rutin.) 

QUERCITRIN— A  yellow  crystalline  dyestuff  of  glucoside 
character  (C21H20On,2H2O)  extracted  by  alcohol  from  the 
bark  of  the  Quercus  tinctoria,  which  yields  quercitin 
(C15H10O7)  and  rhamnose  (C6H12O5)  upon  hydrolysis. 

QUERCITRON — The  powdered  bark  of  Quercus  tinctoria,  the 
extract  of  which  contains  quercitrin  together  with  other 
substances  ;  used  in  tanning  and  in  dyeing  textiles. 

QUICKLIME— See  Calcium. 

26 


402  QUICK  SI  L  VER RADIA  TION 

QUICKSILVER— See  Mercury. 

QUILLAYA  (Quillaja) — /The  bark  of  Quillaya  saponaria,  from 
Bolivia,  Peru,  and  Chili,  which  yields  a  soapy  kind  of 
infusion  containing  saponin  which  is  used  for  washing,  as 
a  foam  producer  in  soft  drinks,  for  shampooing,  and  as  an 
emulsifier.  (See  Saponin.) 

QUINIC  ACID  (C7H12O6)— A  white  crystalline  substance  found 
in  coffee  beans,  quinine  bark,  the  common  holly,  and  the 
leaves  of  some  conifers  and  the  cedar ;  soluble  in  water 
and  alcohol ;  melting-point,  160°  C. 

.      QUINIDINE— See  Cinchona. 
QUININE— See  Cinchona. 
QUINOL — See  Hydroquinone. 

QUINOLINE — A  colourless,  highly  refractive  liquid  of  peculiar 
characteristic  odour,  present  in  coal  tar,  and  produced 
synthetically  from  aniline.  It  is  a  tertiary  amine  which 
is  soluble  in  water  and  alcohol,  boils  at  239°  C.,  has  a 
sp.  gr.  1*08,  and  is  used  in  medicine  and  for  preserving 
anatomical  specimens. 

QUINONES — A  group  of  yellow  compounds  used  in  dyestuffs, 
obtained  from  benzene  and  its  derivatives,  by  methods 
which  replace  2  atoms  of  hydrogen  by  2  of  oxygen — for 
example,  quinone  (C6H4O2),  which  is  prepared  from  a 
solution  of  quinol  by  the  addition  of  chromic  acid. 

RACEMIC  ACID  ((C4H6O6)2H2O)— A  transparent  crystalline 
form  of  tartaric  acid  (C4H6O6)  obtained  from  tartar  mother- 
liquor  devoid  of  the  power  of  turning  the  plane  of  polarized 
light,  and  therefore  termed  "inactive."  It  is  soluble  in 
water,  melts  at  205°  C.,  and  admits  of  division  into  two 
modifications  :  the  one  known  as  dextro-tartaric  acid,  which 
turns  the  polarized  light  plane  to  the  right ;  and  the  other 
as  laevo-tartaric,  which  affects  it  to  the  left.  (See  Tartaric 
Acid.) 

RACEMIC  COMPOUNDS  are  mixtures  of  equal  parts  of  the 
dextro  and  laevo  modifications  (isomers)  of  compounds,  and 
are,  in .  consequence,  optically  inactive — racemic  acid,  for 
example. 

RADIANT  MATTER— See  Radio-activity. 

RADIATION— Throwing  out  or  dispersion— as,  for  example, 
the  heat  radiated  from  an  open  fire.  (See  Heat.) 


RA  DIG  A  LS—RA  DIO-A  CTI VITY  403 

RADICALS  (or  RADICLES)— Groups  of  atoms  which  behave 
in  replacement  value,  as  atoms  in  a  number  of  com- 
binations— for  example,  the  group  CH2  in  the  homo- 
logous "  paraffin  "  series  of  hydrocarbons  ;  the  group  HO 
in  the  alcohols  ;  the  group  C3H5  (glyceryl)  in  fats  ;  the 
group  NO2  in  nitric  acid  and  many  explosives;  and  the 
group  SO2  in  sulphuric  acid.  These  radicals  may  be  mono, 
di,  or  trivalent,  etc. — that  is  to  say,  capable  of  replacing 
one,  two,  or  three  monovalent  atoms.  In  the  case  of 
nitric  acid  (HNO3),  the  constitutional  formula  is  therefore 
expressed  as  water  in  which  an  atom  of  hydrogen  is  replaced 
by  NO2— viz.,  H,NO2,O;  that  of  ethyl  alcohol  (C2H6O)  as 
C2H5HO  ;  and  sodium  ethoxide  as  C2H5NaO. 

RADIO-ACTIVITY  is  a  phenomenon  which  appears  to  depend 
upon  the  expulsion  of  certain  electrons  from  substances, 
thus  explaining  the  apparent  conversion  of  one  kind  of 
matter  into  another  as  referred  to  under  the  heading  of 
Atoms  ;  and  this  is  done  without  materially  disturbing  the 
general  character  and  properties  of  the  residual  substance 
in  its  relation  to  the  groupings  (when  dealing  with  elements) 
of  the  periodic  law  (see  Lead).  In  other  words,  elements 
may  exist  generally  identical  in  chemical  and  physical 
properties,  but  having  different  atomic  weights. 

Crookes  originally  found  that  when  an  electric  current 
was  passed  through  a  glass  tube  previously  exhausted  of 
air  to  a  great  extent,  certain  rays  looking  like  light,  pass 
from  the  cathode  to  the  anode,  although  the  anode  is  the 
pole  at  which  the  current  enters.  These  rays,  called 
"  radiant  matter,"  are  able  to  drive  a  little  vane  placed  in 
their  path — that  is,  to  exercise  some  small  mechanical 
pressure.  These  emanations  are  now  regarded  as  electrons, 
and  will  pass,  as  afterwards  ascertained,  through  thin  sheets 
of  metal.  The  cathode  rays  may  be  made  to  converge  by 
the  use  of  an  aluminium  cup,  thus  producing  a  green 
phosphorescent  spot  on  the  glass.  They  travel  in  straight 
lines,  and  cast  a  strong  shadow  from  any  intervening  object 
placed  in  their  path ;  they  also  develop  great  heat,  which 
may  rise  to  the  melting-point  of  platinum. 

The  so-called  X  rays  are  a  form  of  light  lying  beyond  the 
visible  end  of  the  spectrum  (see  Rontgen  Rays),  and 
Becquerel,  in  his  search  for  the  possiMe  emission  of  Rontgen 
rays  by  fluorescent  substances,  encountered  rays  which  are 
considered  to  be  corpuscular.  For  example,  a  double  salt 
of  uranium  and  potassium,  without  exposure  to  light,  was 
found  to  emit  rays  which  affected  a  photographic  plate,  and 


404  RA  DIO-A  CTI VITY—RA  DI UM 

RADIO-ACTIVITY  (Continued)— 

this  was  the  first  ascertained  instance  of  so-called  radio- 
activity. This  discovery  was  followed  by  that  of  Curie  and 
his  wife,  to  the  effect  that  the  activity  of  the  uranium 
compounds  is  due  to  the  presence  in  them  of  some  other 
very  active  substance — viz.,  radium,  which  proved  to  be  a 
million  times  more  active  than  uranium. 

Then  it  was  found  that  radium  itself  emits  three  different 
types  of  radiation  :  one  known  as  the  alpha  rays,  which  are 
unable  to  pass  through  a  few  sheets  of  paper ;  another,  the 
beta  rays  which  can  be  cut  off  by  a  thick  sheet  of  lead, 
and  the  gamma  rays,  of  more  intensely  penetrating 
character.  The  alpha  rays  are  regarded  as  atoms  of  helium, 
the  beta  rays  as  identical  with  Crookes's  cathode  rays,  whilst 
the  gamma  rays  are  viewed  as  identical  with  or  similar  to 
the  X  rays. 

Uranium  is  a  typical  radio-active  substance,  and  by  the 
loss  of  an  alpha  ray  is  transformed  to  a  modified  element, 
which  by  the  loss  of  a  beta  ray  is  again  changed  into 
a  further  modified  elemental  form,  thus  illustrating  the 
atomic  changes  referred  to  under  the  respective  headings  of 
Atoms,  Elements,  and  Radium. 

According  to  Rutherford,  the  a-rays  obtained  from  the 
nuclei  of  helium  atoms  constitute  a  powerful  and  effective 
agent  for  disintegrating  and  simplifying  the  nuclei  of  atoms 
generally,  and  he  supposes  that  helium  is  one  of  the  bricks 
of  which  the  heavier  atoms  are  built  up,  and  that  hydrogen 
is  one  of  the  products  of  the  disintegration  of  oxygen. 

Among  the  outstanding  problems  to  be  satisfactorily 
solved  is  the  nature  and  structure  of  the  nuclear  parts  of 
atoms,  but  it  is  sometimes  alleged  that  they  are  built  up  of 
hydrogen  nuclei  and  electrons. 

RADIUM  (Ra) — Atomic  weight,  226.  Radium  is  a  very  rare, 
bright,  white  metal,  melting  at  700°  C.,  and  one  of  the 
more  recently  discovered  elements,  the  chief  sources  of 
which  are  cavnotite  and  pitch-blende  (minerals  found  in 
Cornwall,  Colorado,  and  elsewhere,  500  tons  of  Colorado 
carnotiU  yielding  about  i  gramme  of  radium).  It  has 
remarkable  properties  and  is  supposed  to  be  an  atomic 
decomposition  product  of  the  metal  uranium,  resembling 
barium  in  its  chemical  properties  and  yielding  crystalline 
salts,  which  are  luminous  in  the  dark,  radio-active  and 
emit  heat :  they  are  thus  able  to  maintain  a  temperature 
higher  than  that  of  their  surroundings. 

The  chloride  (RaCl2)  is  a  soluble  yellowish-white  crystal- 


RADIUM— RAPE-SEED  OIL  405 

RADIUM  (Continued)— 

line  salt,  which,  mixed  with  calcium  sulphide,  is  used  in 
making  a  luminous  paint ;  whilst  the  bromide  (RaBr2)  is  a 
white  crystalline  salt  similarly  employed,  and  both  are  used 
in  medicine  (chiefly  in  the  treatment  of  cancer). 

The  radiations  of  radium  are  used  as  a  curative  agency 
in  medical  science  and  its  rays  are  very  destructive  of 
animal  tissues.  In  emitting  these  radiations  it  undergoes 
spontaneous  decomposition,  giving  out  heat  continually,  and 
yielding  some  seven  successive  radio-active  disintegration 
products,  including  niton,  radio-lead  (see  Lead),  and  helium. 
(See  Atoms,  Elements,  and  Radio-activity.) 

It  has  been  calculated  that  radium  disintegrates  at  such  rate 
that  the  time  required  for  one-half  of  any  given  quantity 
to  break  up  into  other  elements  is  about  1,670  years. 

The  penetrating  radium  rays  are  capable  of  bringing 
about  many  chemical  changes,  among  which  may  be 
instanced  their  action  on  toluene,  resulting,  it  is  stated,  in 
the  production  of  benzaldehyde  and  benzoic  acid. 

RAFFINOSE  (Melitriose)  (C18H32O16,5H2O)— A  soluble  carbo- 
hydrate, very  like  cane  sugar,  but  tasteless,  found  in  the 
sugar-beet  and  in  molasses.  It  is  dextro-rotatory  and  splits 
up  into  other  sugar-like  bodies  upon  inversion. 

RAMIE  (Rhea  Ramie,  or  Chinese  Grass) — The  fibre  of  several 
varieties  of  the  genus  Boehmeria,  or  the  Rhea  of  Assam, 
now  grown  in  India  and  Italy,  and  said  to  be  nearly  three 
times  stronger  than  Russian  hemp.  It  contains  a  large 
quantity  (22  to  35  per  cent.)  of  gum ;  is  used  in  China  for 
making  mats  and  sails  ;  in  Saxony  in  making  tapestry, 
tablecloths,  damasks,  etc.,  and  is  the  principal  yarn  from 
which  gas  mantle  fabrics  are  knitted  and  woven. 

RANCIDITY  of  butter,  fats  and  oils,  results  from  chemical 
changes  brought  about  by  enzymes  produced  by  micro- 
organisms and  the  action  of  air,  light  and  moisture. 

RAPE-SEED  OIL  (Colza  Oil)— A  dark,  non-drying,  fatty  oil 
of  unpleasant  odour  extracted  by  pressure  from  rape-seed, 
a  plant  of  the  cabbage  tribe  of  the  genus  Brassica  (Brassica 
campestris).  The  best  rape-seed  comes  from  Shanghai 
and  Hankow  in  a  number  of  varieties,  and  a  considerable 
quantity  is  raised  in  India  and  Japan.  It  yields  from  33  to 
50  per  cent,  of  oil,  which  is  yellowish  in  colour ;  has  a 
sp.  gr.  of  0-9132  to  0-9168  ;  a  saponification  value  of  170  to 
179;  refractive  index,  1*472;  iodine  value,  94  to  100,  and 


4°6  RAPE-SEED  OIL— REFLECTION 

RAPE-SEED  OIL  (Continued)— 

solidifies  below  o°  C.  It  is  used  to  some  extent  for  illumin- 
ating purposes,  but  chiefly  for  oiling  woollen  stuffs  and  as  a 
lubricant. 

REAGENTS  —  Solutions  of  various  chemicals  used  for  testing 
purposes  in  qualitative  analysis.  They  comprise  strong 
hydrochloric,  nitric,  and  sulphuric  acids  ;  dilute  solutions  of 
the  same  acids  (of  strength  i  part  to  4  parts  water)  ;  and 
various  salts  containing  about  5  per  cent,  of  the  respective 
substances — that  is  to  say,  5  grammes  by  weight  per 
100  c.c.  dissolved  in  water. 

For  use  in  the  practice  of  volumetric  analyses,  solutions 
of  known  strength,  or  so-called  "  standard  solutions,"  are 
employed,  the  quantities  of  the  constituents  bearing  the 
same  relation  to  each  other  as  the  numbers  which  express 
their  chemical  equivalents.  When  they  are  made  of  such 
strengths .  that  a  litre  (1,000  c.c.)  contains  equivalent 
weights  in  grammes — for  example,  36'5  grammes  (NaCl)  in 
1,000  c.c. — they  are  termed  "  normal  standard  solutions." 

REALGAR— See  Arsenic. 

RECTIFICATION— Purification  of  a  volatile  liquid  by  distilla- 
tion ;  for  example,  a  second  distillation  (redistillation)  of 
alcoholic  liquids  is  an  act  of  rectification. 

REDDLE  (Ruddle) — An  earthy,  ochreous  ore  of  iron,  from 
haematite  deposits,  used  by  farmers  for  making  a  paste  to 
mark  sheep. 

RED  ANTIMONY— See  Antimony,  p.  34. 
RED-LEAD  (Minium)— See  Lead,  p.  288. 

REDONDA  PHOSPHATES— Natural  phosphates  of  iron  and 
aluminium  found  in  the  Islands  of  Redonda  and  Alta  Vela. 

REDUCING  AGENTS — Substances  are  said  to  act  as  reducing 
agents,  when,  for  example,  oxygen  is  removed  in  some 
degree  from  an  oxide  by  combination  with  hydrogen  or 
carbon.  Red-lead  is  thus  reduced  to  metallic  lead  by 
strongly  heating  it  upon  a  piece  of  charcoal.  Reduction 
can  be  effected  by  the  addition  of  hydrogen  to  an  organic 
compound  by  the  action  of  sodium  amalgam.  The  manu- 
facture of  aniline  is  carried  out  by  a  reducing  action.  (See 
Aniline. ) 

REFLECTION — A  luminous  ray  projected  upon  a  mirror  is 
thrown  back  or  reflected  at  an  angle,  and  polished  objects 
reflect  a  great  part  of  the  heat  which  falls  upon  them. 


REFRA  CTION—REFRA  CTORIES  407 

REFRACTION — The  effect  which  is  produced  when  a  ray  of 
light  passes  from  one  medium  to  another  ;  making  a  body 
partially  immersed  in  water  look  as  if  it  were  broken. 

REFRACTOMETERS — Instruments  for  measuring  the  velocity 
of  propagation  of  light  in  a  substance,  this  velocity  being 
inversely  proportional  to  the  refractive  index  of  substances. 
The  refractive  index  is  constant  for  every  pure  substance 
under  standardized  conditions  of  temperature  and  pressure. 
There  are  a  number  of  refractometers  for  various 
purposes,  one  of  the  best  for  purely  scientific  work  being 
the  "  Pulfrich."  The  so-called  "  butyro  "-refractometer  is 
largely  used  for  oils  and  fats,  while  another  all-round  useful 
instrument  is  the  "  Abbe,"  which  is  also  utilized  in  the 
determination  of  melting-points. 

REFRACTORIES  are  substances  difficult  to  fuse,  and  implies 
materials  employed  in  the  construction  of  furnaces,  ovens, 
kilns,  retort  settings,  furnace  hearths,  stoves,  crucibles,  etc., 
on  account  of  their  resistance  to  heat,  abrasion,  strain,  and 
the  action  of  gases  and  the  chemical  compounds  to  which 
they  are  exposed  in  such  use. 

Clays,  fireclays,  and  silica  in  the  forms  of  flint,  quartz, 
sandstone,  and  ganister,  are  described  as  acid  refractories, 
containing  as  they  do  silicic  acid  alone  or  in  combination 
(as  in  the  clays)  with  alumina ;  while  chromite  (natural 
chromate  of  iron),  graphite,  and  plumbago,  are  neutral  in 
character,  and  bauxite,  lime,  magnesia,  and  zirconia  are 
examples  of  so-called  basic  refractories. 

Fireclay,  being  acidic  in  character,  is  destroyed  when 
heated  with  bases  such  as  lime;  and  magnesia,  being  basic,  is 
destroyed  when  heated  with  an  acid  refractory  such  as  clay. 

Mica,  talc,  alumina,  and  carborundum  are  further 
instances  of  refractories. 

The  mineral  chromite  is  largely  used  in  the  manufacture 
of  bricks  for  lining  steel  and  copper  smelting  furnaces. 
They  usually  contain  about  33  per  cent,  chromic  oxide, 
with  less  than  6  per  cent,  of  silica,  the  bricks  being  com- 
pounded by  mixing  the  powdered  ore  with  water  and  a 
binding  material  such  as  tar,  into  paste  form,  moulding, 
drying,  and  burning  up  to  1,460°  C.  in  kilns. 

Refractory  mortars  and  cements  employed  for  joining, 
patching,  or  binding,  and  as  washes  over  surfaces,  are 
sometimes  made  of  corresponding  materials,  but  slightly 
more  fusible  than  those  to  be  treated,  so  that  a  vitrified 
bond  is  formed  upon  the  application  of  strong  heat. 

Zirkite  cement  consists  wholly  of  zirconia,  finely  ground 


408  REFRA  CTORIES-REGELA  TION 

REFRACTORIES  (Continued)— 

and  made  into  a  paste  with  water,  while  silica  bricks  are 
generally  used  in  the  construction  of  electric  furnaces. 

The  clays  used  in  the  making  of  porcelain  and  earthen- 
ware, lose  their  chemically  associated  water  when  heated  to 
from  480°  to  600°  C.,  and  the  temperature  used  in  making 
non-absorbent  or  vitreous  porcelain  varies  from  1,250°  to 
1,550°  C.,  while  that  employed  for  porous  or  non-vitreous 
ware  ranges  from  1,150°  to  1,250°  C. 

In  his  work  on  "  Refractories,"  by  A.  B.  Searle,  it  is 
stated  that  fire  bricks  heated  in  a  darkened  chamber  (as  in 
a  kiln)  exhibit  the  appearance  s  noted  below,  at  various 
given  temperatures : 

Just-visible  red  ...  ...  500°  to  650°  C. 

Cherry            „  ...  ...  850°  to  900°  C. 

Bright            „  ...  ...  1,000°  C. 

Orange       ...  ...  ...  1,100°  C. 

Yellow        ...  ...  ...  1,200°  C. 

White         ...  ...  ...  1,500°  C. 

and  that  they  begin  to  lose  their  shape  when  the  temperature 
reaches  to  from  1,600°  to  1,800°  C. 

A  German  method  of  preparing  ordinary  bricks,  so  as  to 
have  a  refractory  character,  consists  in  coating  them  with 
a  mixture  of  75  per  cent,  carborundum  and  25  per  cent, 
sodium  silicate,  and  after  drying,  slowly  heating,  and  burning 
in  the  mixture. 

REFRIGERATE — To  make  cool.  There  are  processes  for 
refrigerating  perishable  and  other  articles  based  upon  the 
cooling  which  is  produced  by  causing  volatile  liquids  like 
strong  ammonia  and  liquefied  carbon  dioxide  to  assume  the 
vaporous  state.  This  change  of  state  involves  the  con- 
sumption or  absorption,  so  to  speak,  of  heat,  and  is  used 
for  cooling  chambers  in  which  foods,  etc.,  are  kept  A 
kilogram  of  liquid  ammonia  evaporated  at  -  10°  C.  ab- 
sorbs 322-3  calories.  With  regard  to  the  preservation 
of  meat  and  fish,  it  has  been  shown  that,  by  sufficiently 
rapid  cooling  to  a  temperature  that  corresponds  to  the 
eutectic  of  a  saline  solution,  the  separation  of  frozen  water 
as  a  visible  phase  is  avoided,  so  that  upon  thawing,  the 
system  returns  to  its  original  state.  Processes  of  refrigera- 
tion are  often  used  in  chemical  investigations  and  operations. 
(See  Heat  and  Freezing  Mixtures.) 

REGULATION — The  freezing  of  water  anew,  brought  about  by 
the  reduction  of  pressure,  the  melting-point  of  ice  (o°  C. 


REGELA  TION— RESINS  409 

REGULATION  (Continued}— 

under  a  pressure  of  i  atmosphere)  being  affected  by  the 

alteration  of  pressure  to  a  slight  extent. 
REGULUS  —  Metal  reduced  from  oxides  or  other  compounds 

by  fusion  with  reducing  agents. 

REICHERT-WOLLNY  FAT  VALUES— The  values  of  the 
volatile  fatty  acids  contained  in  fats,  represented  by  the 
amount  of  alkali  required  to  neutralize  them,  as  obtained 
by  a  special  process  of  separation  and  distillation. 

REINSCH'S  TEST  FOR  ARSENIC— Is  based  upon  the  fact  that 
if  a  clean  strip  of  copper  foil  be  immersed  in  an  acidified 
arsenical  solution,  metallic  arsenic  is  deposited  on  the  copper, 
forming  copper  arsenide  (Cu5As2). 

RENNET — An  infusion  of  the  inner  membrane  of  the  fourth 
stomach  of  the  calf,  used  for  coagulating  milk  in  the 
manufacture  of  cheese.  This  coagulation  is  due  to  the 
action  of  an  enzyme  contained  in  the  rennet  which  is  sup- 
posed to  be  of  a  different  class  from  those  other  enzymes 
which  act  either  by  hydrolysis  or  oxidation.  (See  Enzymes.) 

RESINATES — Compounds  of  abietic,  pimaric,  and  sylvic  acids 
(resin  constituents) 

"  RESINITE  "  is  the  name  of  a  sort  of  resin  made  by  the  action 
of  formaldehyde  upon  phenol. 

RESINS — A  class  of  uncrystallizable  vegetable  products  which 
are  insoluble  in  water  as  distinct  from  gums  (properly  so 
called).  They  soften,  as  a  rule,  upon  heating  and  are  more 
or  less  soluble  in  alcohol,  ether,  benzine,  turpentine,  and 
other  solvents.  Many  of  them  are  exudations  from  living 
trees  and  some  of  these  are  supposed  to  result  from 
oxidation  of  the  volatile  or  essential  oils  which  are  secreted 
by  them.  These  exudations  are  sometimes  artificially 
facilitated  by  incisions  made  in  the  trees  as  in  the  case 
of  crude  turpentine. 

Others  are  of  fossil  origin  but  have  been  probably  pro- 
duced by  similar  natural  processes,  while  many  others  are 
extracted  from  plants  by  the  use  of  solvents  such  as  alcohol, 
benzene,  or  volatile  oils.  They  are  mostly  yellow  or  brown 
in  colour  ;  some  are  hard  and  fracture  easily  ;  others  are  soft ; 
and  some  become  electric  when  rubbed.  Descriptions  of  some 
of  the  following  will  be  found  under  their  several  names 
or  under  the  heading  of  Balsams :  Amber,  Ammoniacum, 
Anime,  Asafcetida,  Benzoin,  Burgundy,  Capsicum,  Copaiba, 
Copal,  Dammar,  Dragon's  Blood,  Elemi,  Frankincense, 
Galbanum,  Gamboge,  Guaiacum,  Gambier,  Jalap,  Kino, 


410  RESINS— RESPIRA  TION 

RESINS  (Continued)— 

Kowrie,  Lac,  Mastic,  Opopanax,  Podophyllum,  Sandarach, 
Scammony,  Shellac,  Storax,  Tolu,  and  Valerian.  (See 
also  Balsams,  Gums,  and  Mucilage.) 

The  resins  are  largely  used  in  making  lacs,  varnishes, 
rubber  substitutes,  etc. 

Common  Resin  (Colophony-Rosin) — The  residuum  left 
behind  in  the  retorts  when  crude  turpentine  (as  it  exudes 
from  the  pine-trees  which  produce  it,  and  known  also  as 
galipot,  and  gum  thus)  is  distilled.  It  is  graded  according 
to  colour,  from  B,  the  darkest,  to  W  W,  the  lightest,  and  is 
very  much  used  in  various  industries,  particularly  in  soap- 
making,  having  the  property  of  combining  with  alkalies, 
thus  forming  a  kind  of  soap.  The  saponification  value  of 
American  rosin  is  about  170  to  180,  and  the  iodine  value 
about  122. 

When  rosin  itself  is  subjected  to  destructive  distillation 
by  greater  heat,  it  is  cracked  or  split  up  into  a  number  of 
products,  including  rosin  spirit  and  rosin  oil,  which  pass 
over  with  the  vapours  and  are  condensed,  whilst  a  pitch  is 
left  behind  in  the  retorts.  (See  Rosin  Oil,  Rosin  Spirit, 
Abietic  Acid,  Pimaric  Acid,  and  Wood.) 

Synthetic  Resins — Many  attempts  have  been  made  to 
produce  satisfactory  paint  resins  by  polymerizing  indene 
and  coumarone — two  constituents  of  that  fraction  of  coal- 
tar  naphtha  distilling  between  160°  and  185°  C. — by  means 
of  heat  or  the  action  of  mineral  acids.  The  products  are 
yellowish  to  red  substances  of  resinous  character,  soluble 
in  ether,  turpentine,  acetone,  and  carbon  disulphide,  and  are 
used  in  compounding  rubber  goods,  paints,  and  varnishes. 
The  formula  of  coumarone  resin  (otherwise  known  as 
benzo-furane  resin)  is  given  asC6H4.CH.O.CH.  (See  also 
Ester  Gums,  p.  182.) 

RESORCINEor  RESORCINOL  (C6H6O2or  C6H4(OH)2)  isawhite 
crystalline  phenolic  body  of  antiseptic  character,  which  can  be 
prepared  from  many  resins,  such  as  galbanum  and  asafcetida, 
by  fusion  with  caustic  potash.  It  melts  at  1 10°  C.,  is  soluble 
in  water,  alcohol,  and  ether,  exhibits  a  therapeutical  action 
mildly  resembling  that  of  carbolic  acid,  and  is  the  basis  of 
a  number  of  dyes.  Nitrous  acid,  for  instance,  transforms 
it  into  the  so-called  azo-dyes. 

RESPIRATION  is,  in  essence,  a  chemical  process  whereby  the 
blood  is  purified  by  absorption  of  oxygen  from  the  air 
breathed  into  the  lungs,  carbon  dioxide  and  aqueous  vapour 


RESPIRATION— RETORT  OR  STILL 


411 


RESPIRATION  (Continued)— 

being  exhaled.  The  exhaled  breath  contains  about  4*4  per 
cent,  of  carbon  dioxide  and  10*4  per  cent,  oxygen  as  com- 
pared with  o'4  per  cent,  carbon  dioxide  and  20^96  per  cent, 
oxygen  present  in  ordinary  air.  The  exhaled  air  contains, 
in  addition  to  its  moisture,  traces  of  ammonia  and  organic 
matters  that  make  overcrowded  rooms  unpleasant  and 
unhealthy — hence  the  importance  of  ventilation.- 

It  is  by  combination  of  the  oxygen,  breathed  into  the 
body,  with  the  haemoglobin  of  the  blood-corpuscles  that  it  is 
carried  to  all  parts  of  the  tissues,  the  latter  in  their  turn 
giving  up  carbon  dioxide,  water,  urea,  and  other  excremen- 
titious  products.  (See  Haematine.) 

The  water  given  off  in  the  exhaled  breath  in  twenty-four 
hours  has  been  estimated  at  311  grms.,  or  nearly  n  oz., 
and  the  carbon  (in  the  form  of  carbon  dioxide)  at  from 
7-144  to  117  oz.  (See  also  Air.) 

RETENE  (C18H18)— A  hydrocarbon  accompanying  pyrene, 
etc.,  in  coal-tar  distillate  which  boils  above  360°  C.  (See 
Pyrene.) 

RETORT  or  STILL — The  illustration  given  below  shows  an 
apparatus  employed  for  distilling  purposes,  consisting  of  the 
glass  retort  A  (in  which  the  liquid  to  be  distilled  is  introduced 
through  the  tubulure,  which  can  be  closed  with  a  glass 


This  figure  shows  a  thermometer  passing-  throug-h  the  cork  fitting- 
the  tubulure  of  the  retort. 

stopper  or  cork)  from  which  the  vaporized  substance  passes 
to  the  condenser.  The  retort  is  held  in  position  by  a  retort- 
stand,  the  body  resting  upon  a  sheet  of  wire  gauze  placed 
on  one  ring  of  the  stand,  while  the  neck  of  the  retort  can 
be  secured  or  held  in  position  by  a  smaller  ring  of  the  same 
stand.  The  heat  is  applied  by  a  lamp  placed  below  the  retort. 
Liebig's  condenser  (B)  is  a  simple  appliance  for  assist- 
ing, by  cooling,  the  condensation  of  vapours  carried  over 
from  retorts,  It  consists  of  a  water-jacket  surrounding 


412  RETORT  OR  STILL— RHUS 

RETORT  or  STILL  (Continued) — 

a  tube  (connected  with  the  retort),  through  which  a  stream 
of  cold  water  is  made  to  pass,  entering  by  the  attached 
tube,  C,  at  the  lower  end,  the  warmer  water  thus  replaced 
passing  out  of  the  condenser  through  the  upper  attached 
tube,  D.  The  vapour  passing  away  from  the  retort  through 
the  neck  and  tube  is  thus  cooled  and  condensed  to  the 
liquid  state,  and  flows  out  at  E  into  any  receiver,  F,  that 
may  be  placed  there.  Gas  retorts  for  roasting  coal  in  the 
process  of  coal  gas  making,  are  constructed  on  the  same 
principle  as  laboratory  retorts. 

REVERBERATORY  FURNACE— A  furnace  so  constructed 
that  the  fuel  flame  in  passing  to  the  chimney-shaft  is  made 
to  pass  (reverberate)  over  the  materials  lying  upon  its  bed — 
these  materials  being  the  substances  to  undergo  chemical 
change  by  action  of  the  heat  thus  imposed. 

RHAMNOSE  (Iso-dulcite)  (C6H12O5,H2O)  — A  colourless 
crystalline  carbohydrate  or  sugar-like  body  which  melts 
at  93°  C.,  obtained  from  several  glucosides  by  hydrolysis. 
Quercitrin  extract  (from  Rhamnus  tinctoria)  yields  rhamnose. 

RHATANY  ROOT  (Krameria) — The  dried  root  of  Krameria 
triandra  (from  Peru,  Bolivia,  and  Brazil),  containing  from 
8  to  20  per  cent,  of  a  tanning  material. 

RHODAMINES — A  series  of  dyes  nearly  related  to  fluorescein, 
being  colourless  basic  bodies  of  which  the  salts,  such  as  the 
sulphate,  are  red. 

RHODIUM  (Rh) — Atomic  weight,  103  ;  sp.gr.,  12-1.  A  metallic 
element  found  in  platinum  ores  and  belonging  to  the  same 
group.  It  is  white,  lustrous,  has  a  high  melting-point 
(above  that  of  platinum — about  1,970°  to  2,000°  C.),  and  is 
used  in  the  construction  of  electrical  pyrometers.  Three 
oxides  are  known— viz.,  RhO,  Rh2O3,  and  RhO2,  and  its 
salts  include  two  chlorides  (RhQ2  and  Rh2Cl6),  two 
sulphides  (RhS  and  Rh2S3),  also  a  sulphate  corresponding 
to  the  sesquioxide  (Rh2(SO4)3). 

RHUBARB  (Rheum),  the  dried  rhizome  of  Rheum  officinale,  of 
which  many  species  grow  wild  on  the  high  lands  of  Central 
Asia,  and  many  are  cultivated;  used  for  its  purgative 
properties.  The  juice  of  the  stems  contains  oxalic,  malic, 
and  citric  acids. 

The  root  of  rhubarb  contains  chrysophanic  acid  and 
other  substances.  English  garden  varieties  (Rheum  undu- 
latum  and  Rh.  hybridum)  are  used  as  food. 

RHUS  (Sumach) — There  are  many  species  rich  in  tannicacid. 


RICE—RONTGEN  RAYS  413 

BICE — A  well-known  grain  (Ovyza  sativa)  (of  which  the  chief  con- 
stituent is  starch)  largely  grown  in  Asia,  South  America, 
and  the  U.S.A.  The  sp.  gr.  of  rice  is  about  1-43  to  1-46, 
and  it  contains  from  73  to  78  per  cent,  starch,  associated 
with  fat  varying  from  0-5  to  7  per  cent.,  albuminoids 
from  7  to  8-5  per  cent.,  water  about  13  per  cent.,  and  small 
proportions  of  mineral  and  other  substances.  Polishing 
decreases  the  nutritive  elements  in  rice.  The  polishings 
contain  oil  and  are  usually  sold  as  a  fertilizer  or  feeding- 
stuff.  (See  Starch  and  Vitamines.) 

BICINOLEIC  ACID  (C18H34O3,  or  C17H32(OH)COOH)— The 
glyceride  of  this  fatty  acid  makes  up  some  80  per  cent,  of 
castor  oil,  and  occurs  also  in  curcas  oil.  It  is  yellowish, 
thick,  solidifies  at  15°  C.,  has  a  sp.  gr.  of  0-945  '•>  *s  soluble 
in  alcohol,  ether,  etc.,  and  is  used  in  soap-making,  the 
manufacture  of  Turkey-red  oils,  and  dressing  of  textiles. 
BOBUEITE — See  Explosives. 

EOCHELLE  SALT  (KNaC4H4O6,4H2O)— A  double  tartrate  of 
potassium  and  sodium,  being  a  colourless  crystalline  com- 
pound, soluble  in  water,  used  in  the  preparation  of  certain 
baking-powders. 
EOCK  CEYSTAL-See  Silicon. 
EOCK  SALT— See  Sodium. 
EOMAN    CEMENT — A    form    of    hydraulic    cement.      (See 

Cement.) 

RONTGEN  BAYS  (X  Eays)  are  certain  rays  given  off  from  the 
cathode,  comparable  with  light  of  extremely  small  wave- 
length, and  are  produced  by  passing  an  electric  current 
through  a  highly  vacuous  glass  tube  and  deflecting  the  rays 
by  a  mirror.  They  have  the  power  of  penetrating  solid 
substances,  such  as  animal  tissues,  paper,  wood,  and  some 
metals,  and  acting  on  a  photographic  plate  behind  the 
object  to  be  radiographed.  It  is  thus  possible  to  obtain 
shadowgraphs  of  portions  of  the  human  skeleton,  as  the 
bones  are  not  so  easily  penetrated  as  are  the  skin,  muscle, 
etc.  The  discovery  of  these  rays  has  proved  of  great 
value  in  the  examination  of  crystal  structure ;  also  in 
practical  surgery  for  locating  bullets,  etc.,  in  the  human 
body  and  for  indicating  the  nature  of  fractures  and  dis- 
tinguishing between  strains  and  dislocations. 

X  Eays  are  now  applied  industrially  for  the  detection  of 
blow-holes  and  cracks  in  metals  and  brazings,  the  examina- 
tion of  ferro-concrete,  and  the  internal  parts  of  clocks  and 
watches,  motor  tyres,  electric  cables,  cricket  and  golf  balls, 
etc.  (See  Atoms,  Electrons,  and  Radio-activity.) 


414  ROSANILINES— ROSIN  OIL 

ROSANILINES — The  aminated 'bases  of  fuchsine  or  magenta 
dyes. 

The  rosanilines  are  colourless,  crystalline  compounds, 
and  only  form  dyes  when  united  with  an  acid.  Rosaniline 
(C20H21N3O)  and  para-rosaniline  (C19H19N3O)are  obtained 
by  precipitation  of  their  salts  with  alkalies. 

The  actual  dyes  are  the  salts  of  these  compounds,  and 
include  magenta,  otherwise  known  as  fuchsine  (C20H20N3C1), 
rosaline  nitrate  (C20H20N3(NO3)),  rosaniline  acetate 
(C20H20N3(C2H3O)),  and  para-fuchsine  (C19H1?N3C1). 
These  all  dye  wool  and  silk  without  a  mordant,  giving  a 
magnificent  fuchsine-red  colour  in  solution,  but  are  them- 
selves in  crystalline  form,  of  a  bright  metallic  green  lustre. 
They  are  soluble  in  hot  water  and  alcohol. 

Rosaniline  yields  rosolic  acid  by  treatment  with  nitrous  acid. 

The  formulae  of  rosaniline  and  para-rosaniline  may  be 
shown  as  below  : 

Rosaniline.  Para-rosaniline. 

XC6H4NH2.  xCfiH4NH2. 

C.OH^-C6H4NH2.  C.OH<^  ~C6H4NH2. 

XC6H3.CH3.NH2.  XC6H4NH2. 

ROSE  OIL.— See  Attar  of  Roses. 
ROSEINE— See  Fuchsine. 

ROSEMARY  (OIL  OF) — The  essential  oil  of  Rosmavinus  officinak, 
containing  a  terpene  and  other  substances,  and  used  in  per- 
fumery. Sp.  gr.  0-9  to  0*92,  and  rotation  4-0°  to  +15°. 

ROSIN— See  Resins. 

ROSIN  OIL — The  fraction  from  the  destructive  distillation  of 
rosin  which  comes  over  after  the  rosin  spirit,  and  up  to 
about  400°  C.,  constituting  the  bulk  of  the  total  distillate 
It  exhibits  a  blue  fluorescence  and  is  a  complicated 
mixture  of  hydrocarbons,  phenols,  and  free  rosin  acids, 
ranging  from  9  to  30  per  cent.  The  last-named  sub- 
stances can  be  removed,  together  with  some  of  the  dark 
colour,  by  treatment  with  caustic  soda.  In  general,  it 
resembles  mineral  oil,  and  is  of  sp.  gr.  varying  from  0-92 
up  to  over  1-12.  There  are  a  number  of  grades,  some  being 
practically  colourless,  and  known  as  "pine  oil,"  while 
another  is  dark  blue,  and  known  as  "  blue  rosin  oil,"  or 
"  blue  billy."  It  is  soluble  in  ether,  turpentine,  carbon 
disulphide,  etc.,  and  finds  use  as  a  lubricant  and  as  an 
adulterant  of  boiled  linseed  and  other  oils. 


ROSIN  SPIRIT— RUBBER  4*5 

EOSIN  SPIRIT  (Pinoline)  is  a  complex  mixture  of  hydrocarbons 
and  rosin  acids,  forming  the  distillate  from  the  destructive 
distillation  of  rosin  that  comes  over  below  150°  C.,  and 
amounting  to  from  2^  to  5  per  cent,  of  the  total  distillate. 
It  can  be  freed  from  associated  acids  by  caustic  soda,  or 
refined  by  agitation  with  strong  sulphuric  acid  and  subse- 
quent redistillation.  When  rectified,  it  has  a  sp.  gr.  of 
about  0-856  to  0-883,  is  miscible  with  petroleum  spirit  and 
turpentine,  and  is  used  as  a  substitute  for  turpentine  in  the 
paint  and  other  trades. 

ROSOLIC  ACID  (C20H1(?O3)— A  beautiful  green-coloured  crys- 
talline substance  with  a  metallic  lustre  and  melting-point 
270°  C.,  chemically  related  to  aurine.  It  is  soluble  in 
alcohol  and  ether,  and  is  used  in  dyestuffs. 

ROTATORY  POWER— See  Polarization. 

ROTTEN  STONE— A  mineral  powder — disintegrated  rock  of 
limestone  nature — found  near  Bakewell  in  Derbyshire  and 
elsewhere,  containing  a  large  proportion  of  alumina ;  highly 
prized  for  polishing  purposes. 

ROUGE — A  common  name  for  an  amorphous  form  of  ferric 
oxide,  employed -for  polishing  glass,  etc.;  prepared  by  dis- 
tilling ferrous  sulphate. 

RUBBER  or  CAOUTCHOUC  —  This  well-known  substance  is 
the  concreted  juice  (latex)  of  certain  tropical  trees,  including 
the  Siphonia  elastica,  S.  cahucha,  Jatropha  elastica,  Ficus 
elastica,  Valea  gwnmifeva,  Hevea  caoutchouc,  Hancoria  speciosa, 
and  Urceola  elastica — the  fourth  and  last  named  being  natives 
of  India  and  sufficiently  explaining  the  name  India-rubber. 
Rubber  is  imported  from  various  parts  of  South  America, 
Asia,  and  Africa,  the  Para  rubber  being  the  best  in  quality, 
although  70  to  80  per  cent,  of  the  world's  supply  of  rubber 
is  now  produced  within  the  British  Empire.  The  Ocotillo, 
or  candleweed,  of  Arizona,  is  also  stated  to  yield  a  kind  of 
rubber  to  the  extent  of  200  Ibs.  of  gum  to  the  ton. 

The  rubber-juice,  or  latex,  has  a  tendency  to  coagulate 
in  the  collecting  cups,  and  to  prevent  this  a  dilute  solution 
of  formaldehyde,  ammonia,  sodium  carbonate,  or  sodium 
sulphite — preferably  the  latter — is  now  used.  The  sub- 
sequent coagulation  can  be  effected  by  chemical,  physical, 
and  biological  methods,  but  acetic  acid  in  the  proportion 
of  i  part  to  1,000  parts  latex,  is  generally  employed  as  the 
best  coagulant. 


416  RUBBER 

RUBBER  (Continued)— 

The  total  production  of  rubber  in  1920  has  been  esti- 
mated at  360,000  tons. 

In  the  pure  state,  caoutchouc  is  white,  but,  as  known  in 
commerce,  it  is  brownish -black  in  colour,  supple,  elastic, 
tenacious,  very  combustible,  a  bad  conductor  of  heat,  and  a 
non-conductor  of  electricity. 

Below  o°  C.  it  becomes  rigid  and  brittle  ;  it  softens 
when  heated,  and  begins  to  melt  at  120°  C. 

Chemically,  caoutchouc  is  a  hydrocarbon  allied  to  gutta- 
percha  and  turpentine,  and  can  be  made  synthetically  from 
isoprene  (C5H8) — a  volatile  hydrocarbon  liquid  derived  from 
turpentine. 

In  sheet,  tape,  or  thread  form,  rubber  may  be  stretched 
very  considerably  without  permanent  loss  of  elongation. 
It  is  soluble  in  turpentine,  naphtha,  and  benzene,  and  is 
extensively  used  in  the  manufacture  of  motor  tyres,  railway 
buffers,  overshoes,  macintosh  garments,  the  cores  of  golf 
balls,  and  many  other  articles. 

When  rubber  is  immersed  in  a  bath  of  melted  sulphur  at 
125°  C.  it  takes  up  as  much  as  from  15  to  20  per  cent.,  but 
only  2  or  3  per  cent,  is  really  in  chemical  combination  in 
the  vulcanized  rubber,  as  the  bulk  can  be  dissolved  out. 
At  a  higher  temperature,  vulcanite  or  ebonite  is  produced  and 
this  product,  unlike  ordinary  rubber,  is  not  soluble  in  tur- 
pentine and  benzene.  This  process  of  vulcanization  is  known 
as  the  "  hot  cure,"  but  there  is  another  one  called  the  "  cold 
cure,"  which  consists  in  treating  the  rubber  with  a  weak  solu- 
tion of  chloride  of  sulphur  at  ordinary  temperatures,  although 
this  only  results  in  a  superficial  vulcanization,  and  is  not 
very  widely  used.  The  new  gaseous  treatment  to  be  next 
described  is  of  great  promise :  as  the  two  gases  are  absorbed 
alternately  by  the  rubber  and  by  chemical  reaction  between 
them,  sulphur  is  deposited  throughout  the  material  in  a  very 
finely  divided  or  atomic  form,  thereby  securing  thorough 
vulcanization. 

It  consists  in  exposing  the  rubber  to  the  action  of  sulphur 
dioxide  and  hydrogen  sulphide  gases  alternately,  and 
is  said  to  yield  a  product  quite  comparable  to  that 
produced  by  the  older  sulphur  process,  without  the 
aid  of  heat.  It  can  also  be  carried  out  in  solution, 
and  is  the  only  process  whereby  rubber  can  be  vulcan- 
ized in  solution,  affording,  at  the  same  time,  the  opportunity 
of  incorporating  with  the  rubber  such  substances  as  saw- 
dust and  leather,  owing  to  the  non-necessity  of  using  high 


RUBBER  417 

RUBBER  (Continued)— 

temperatures,  and  thus  producing  many  mixtures  suitable 
for  wall  and  floor  coverings  and  other  applications. 

The  perishing  of  rubber  goods  proceeds  much  more 
quickly  in  the  vulcanized  articles  than  in  those  of  pure 
rubber.  It  is  said  that  plantation  rubber — that  is,  rubber 
as  it  comes  from  the  growers — may  be  stored  for  years 
without  sensible  loss  of  quality,  and  when  vulcanized  gives 
results  comparable  with  freshly  harvested  material. 
Exposed  to  the  light,  rubber  changes  gradually  in  two  ways, 
in  which  the  oxygen  of  the  air  and  light  take  active  parts — 
namely,  first  in  the  form  of  tackiness,  and  secondly  into  a 
brittle  substance  ;  while  in  darkness  there  is  no  change.  On 
the  other  hand,  the  vulcanized  article  begins  to  depreciate 
from  the  moment  it  is  made.  The  life  of  vulcanized 
rubber  is  prolonged  by  storing  in  air  saturated  with 
moisture  or  petroleum  vapour,  being  thus  protected  from 
oxidation  and  decomposition. 

A  recent  investigation  concerning  the  permeability  of 
rubber  by  gases  has  shown  that  it  is  one  of  dynamic 
equilibrium,  in  which  the  gas  is  dissolved  at  one  side  of  the 
rubber,  at  a  rate  proportional  to  its  solubility  and  partial 
pressure,  and  diffuses  through  the  rubber,  from  which  it 
evaporates  on  the  other  side.  Its  relative  permeability  to 
certain  gases  is  shown  by  the  following  summary  : 

Hydrogen  =  i  *oo. 

Nitrogen     ...  ...  ...  ...  0-16 

Air               ...  ...  ...  ...  0-22 

Argon          ...  ...  ...  ...  0-26 

Oxygen        ...  ...  ...  ...  0-45 

Helium        ...  ...  ....  ...  0^65 

Carbon  dioxide  ...  ...  ...  2*90 

Ammonia    ...  ...  ...  ...  8-oo 

Methyl  chloride  ...  ...  ...  18-50 

Ethyl  chloride  ...  ...  ...  200-00 

It  is  reported  that  the  artificial  production  of  so-called 
"  methyl  rubber "  in  Germany  reached  to  the  extent  of 
165  tons  per  month  during  the  recent  war.  It  is  made 
by  polymerization  of  the  hydrocarbon  dimethylbutadiene 
(primarily  prepared  from  acetone)  by  placing  it  in  her- 
metically sealed  barrels  and  allowing  it  to  remain  undis- 
turbed for  about  six  months  at  a  temperature  of  32°  C., 
the  rubber  being  thus  obtained  as  a  spongy  white  mass 
which  has  to  be  bored  out  of  the  containers.  It  lacks 

27 


418  RUBBER— RUST 

RUBBER  (Continued)  — 

elasticity  when  used  for  making  soft  rubber  goods,  and 
11  elasticators,"  or  oily  materials,  have  to  be  incorporated 
for  such  applications.  It  is  more  useful  in  making  so-called 
"  vulcanites."  (See  Vulcanite.) 

RUBBER-SEED  OIL,  as  extracted  from  the  seeds  of  the  Para 
rubber-tree,  may  possibly  prove  a  substitute  for  linseed 
oil,  but  it  has  been  shown  that  the  seed  depreciates  on 
storage,  and  yields  an  oil  containing  up  to  25  per  cent,  of 
free  fatty  acids,  which  is  not  generally  suitable  for  that 
purpose.  It  exhibits  a  slower  drying  character  as  compared 
with  linseed  oil,  and  it  is  necessary  to  prepare  a  "  boiled  " 
oil  for  commercial  purposes  which  is  free  from  fatty  acids. 

RUBIAN — A  name  sometimes  given  to  the  principle  contained 
in  madder  (the  root  of  Rubia  tinctoria),  of  glucoside 
character,  which  yields  alizarin  and  glucose  by  hydrolysis. 
(See  Alizarin.) 

RUBIDIUM  (Rb)  —  Atomic  weight,  85-45;  sp.  gr.,  1-52.  A 
somewhat  rare  element  met  in  association  with  potassium 
and  sodium  in  the  minerals  lepidolitey  porphyrites,  and  carnal- 
lite.  It  is  a  soft,  silvery-white  metal,  melting  at  38-5°  C., 
and  when  sublimed,  forms  small  needle-shaped  crystals.  It 
can  be  prepared  by  the  electrolysis  of  the  fused  chloride, 
or  heating  the  carbonate  with  carbon.  It  is  capable  of 
decomposing  water  and  takes  fire  in  the  air,  yielding  the 
oxide,  so  that  it  has  to  be  kept,  like  sodium,  under  naphtha. 
It  gives  off  a  green  vapour  when  heated,  and  its  salts,  which 
are  soluble,  resemble  those  of  potassium  in  their  general 
characters. 

RUBY — A  gem  of  clear  red  corundum  (aluminium  oxide).  (See 
Aluminium.) 

RUE  (OIL  OF)  is  obtained  by  distillation  of  garden  rue  (Ruta 
graveolens)  with  water,  and  contains  a  hydrocarbon  with 
other  bodies  in  admixture.  It  is  viscid,  of  strong,  un- 
pleasant odour  and  bitter  taste,  and  is  used  medicinally  as 
an  anti-spasmodic,  etc.  Sp.  gr.,  0-83  to  0-84  ;  and  rotation, 
+  0°  to  +2-30°. 

RUM — An  alcoholic  drink  of  characteristic  odour,  distilled 
from  fermented  molasses  in  the  West  Indies,  and  ordinarily 
containing  about  48  per  cent,  alcohol. 

RUST — The  coating  which  forms  on  iron  articles  exposed  to  air 
and  moisture,  consisting  of  oxides  and  ferrous  carbonate. 


RUSTLESS  STEEL—  SACCHARIC  ACID  419 

RUSTLESS  (STAINLESS)  STEEL—  A  chromium-iron  alloy, 
containing  from  12  to  15  per  cent,  chromium,  and  (for  most 
purposes)  not  more  than  0*45  per  cent,  of  carbon,  now 
largely  used  for  the  manufacture  of  cutlery,  turbine  blades, 
acid  pumps,  and  exhaust  valves  for  aircraft  engines.  It  is 
not  dissolved  by  strong  or  weak  nitric  acid,  nor  attacked 
by  ammonia,  but  sulphuric  and  hydrochloric  acids  attack 
it  readily. 

RUTHENIUM  (Ru)  —  Atomic  weight,  1017;  sp.  gr.,  12-26. 
A  hard,  brittle  metal  of  the  platinum  group,  with  the  ores 
of  which  it  is  found  in  association,  also  as  laurite.  It  is 
practically  insoluble  in  acids  other  than  aqua  regia,  has 
a  higher  melting-point  than  platinum  —  about  1,950°  C.; 
forms  a  chloride  (RuCl4)  which  is  deliquescent  and  very 
soluble  in  water,  and  other  salts  corresponding  to  the 
sesquioxide,  which  is  one  of  the  four  oxides  known  —  namely, 
RuO,  Ru2O3,  RuO2,  and  RuO4.  It  is  also  said  to  form 
a  potassium  combination  (KRuO4)  analogous  to  potassic 
permanganate  (KMnO4). 

RUTILE  —  A  rare  crystalline  mineral  containing  titanium  in  the 
form  of  oxide  (TiO2)  occurring  at  Risor  in  Norway,  at 
Graves  Mountain  in  Georgia,  etc. 

RUTIN  (C27H30O16,3H2O)t—  A  substance  originally  discovered 
in  rue  (Ruta  graveolens)  and  occurring  in  a  number  of  plants, 
including  Viola  tricolor.  It  is  a  glucoside  of  pale  yellow, 
crystalline  character,  sparingly  soluble  in  water  and  alcohol, 
which  upon  hydrolysis  yields  glucose,  rhamnose,  and  quer- 
citin.  The  petals  of  Eschscholtzia  calif  omica  are  said  to  contain 
5  per  cent,  of  rutin. 

RYE—  A  cereal.     (See  Ergot  of  Rye.) 

SABADILLA  —  Seeds  of  Asagraa  officinalis,  growing  in  Mexico, 
Guatemala,  etc.,  from  which  veratrine  is  prepared.  (See 
Veratrine.) 

SACCHARATE,     STRONTIUM—  A     sparingly     soluble     body 
prepared    from    the    mother  -  liquor    of 


molasses  oy  combination  of  the  remaining  crystallizable 
sugar  therein  with  strontium  oxide  ;  it  can  be  decomposed 
by  suspension  in  water  and  treatment  with  carbon  dioxide. 
(See  Sugar.) 

SACCHARIC  ACID  (C6H10O8)  —  A  product  of  the  oxidation  of 
cane  sugar,  glucose,  starch,  etc.,  by  nitric  acid.  It  is 
deliquescent  and  readily  soluble  in  water, 


420  SA  CCHA  RI  METER  —SA  FFRON 

SACCHARIMETER — An  instrument  for  ascertaining  the 
amount  of  sugar  in  a  solution  by  determining  the  specific 
rotatory  power — that  is,  measuring  the  angle  through  which 
the  plane  of  polarized  light  is  turned  when  passing  through 
its  solution,  in  comparison  with  that  of  a  solution  of  known 
strength.  (See  Polarization.) 

SACCHARIN  (Benzoylsulphonic  imide)  (C7H5NSO3)— A  syn- 
thetically prepared  ammonia  derivative  or  imide  compound 
of  one  of  the  sulpho-benzoic  acids  ;  white,  crystalline,  and 
having,  in  common  with  its  hydrated  sodium  salt,  a  sweeten- 
ing power  from  300  to  500  times  that  of  cane  sugar.  It 
is  prepared  from  toluene  and  is  used  as  a  sweetening  sub- 
stitute for  sugar,  particularly  in  diabetic  cases. 

SACCHAROMETER  —  Hydrometer  graduated  to  test  the 
strength  of  sugar  solutions  by  ascertaining  their  density, 
and  reference  to  tables  prepared  from  known  strengths. 

SACCHAROSES  are  carbohydrates  comprising  the  sugars  and 
a  number  of  substances  closely  related  to  them,  together 
with  the  starches  (amyloses)  and  cellulose.  Cane  and  milk 
sugars  are  typical  instances  of  one  series ;  glucose,  fructose, 
and  dextrose  are  members  of  a  nearly  allied  class ;  while  the 
starches,  dextrine  and  cellulose,  are  comprised  in  another 
series.  Some  of  these  individual  substances  are  described 
under  their  several  names,  whilst  a  modern  classification  is 
referred  to  elsewhere.  (See  Carbohydrates.) 

SAFETY  LAMPS,  as  used  by  coal-miners  to  obviate  ex- 
plosions due  to  the  accumulation  of  inflammable  gases,  are 
constructed  on  the  known  fact,  that  a  flame  has  difficulty  in 
crossing  or  passing  through  wire  gauze.  This  is  due  to 
the  conductivity  of  the  metallic  gauze,  which  carries  away 
the  heat  of  the  burning  flame  inside  the  lamp  to  such  an 
extent  that  the  explosive  gas  outside  the  lamp  is  kept 
below  the  temperature  necessary  for  its  ignition.  (See 
Coal.) 

SAFFLOWER  (Carthamus),  derived  from  the  florets  of  Car- 
thamus  tinctorius  of  the  Levant  and  Orient,  is  a  natural  red 
colour  used  as  a  dyestuff  for  cotton  goods  without  a  mor- 
dant, and  for  colouring  purposes. 

SAFFRON  (Crocus) — A  yellow  colouring  matter,  being  the 
stigmas  of  the  saffron  crocus  (Crocus  sativus]  indigenous  in 
Spain,  France,  Greece  and  Asia  Minor;  used  in  cookery,  as  a 
dye,  and  in  medicine.  Spanish  saffron  is  said  to  be  the  best. 


SAFRANINES— SALICYLIC  ACID  421 

SAFRANINES — A  group  of  crystalline  aniline  dyes  of  metallic 
green  lustre,  including  mauve,  related  to  toluylene  red. 
They  are  soluble  in  water,  and  dye  red  and  violet. 

SAFROL  (C10H10O2) — The  essential  constituent  of  sassafras  oil 
(amounting  to  some  78  per  cent.),  and  contained  also  in 
camphor  wood  and  many  other  plants.  It  is  a  clear, 
colourless  oil,  of  sp.  gr.  1*1,  soluble  in  alcohol  and  ether, 
and  used  in  perfumery,  the  manufacture  of  heliotropin, 
piperonal,  etc.  It  has  the  odour  of  sassafras,  and  upon 
cooling  to  —20°  C.  it  crystallizes  in  rhombic  prisms. 
Safrol,  by  oxidation  with  chromic  acid,  yields  heliotropin. 

SAGE  (OIL  OF) — An  essential  oil  distilled  from  the  fresh 
leaves  of  Salvia  officinalis  L.  growing  in  north  Mediterranean 
countries,  containing  the  terpene  named  pinene  (C10H16). 
Sp.  gr.,  0*915  to  0-925  ;  and  rotation,  +  10°  to  +25°. 

SAGO — Consists  nearly  entirely  of  starch,  and  is  prepared  in 
the  islands  of  the  Indian  Archipelago  from  the  pith  of  the 
stems  of  certain  palms,  including  the  Sagus  vumphii  W., 
5.  raffia  Jacq.,  etc. 

SAL-AMMONIAC — An  old  name  for  ammonium -chloride. 

SAL- VOLATILE  —  Commercial  ammonium  carbonate.  (See 
Nitrogen  Compounds,  p.  336.) 

SALICIN  (C13H18O7) — A  glucoside  found  ready  formed  in 
varieties  of  salix  and  populux  (willows  and  poplars),  also  in 
the  flower-buds  of  meadowsweet  and  in  the  green  part  of 
certain  herbaceous  spireas.  In  the  pure  state,  it  is  a  crys- 
talline odourless  substance,  soluble  in  water,  and  possesses 
febrifugal  properties.  In  the  human  body  it  undergoes 
decomposition,  giving  rise  to  the  production  of  salicylic  acid. 
It  is  used  as  a  specific  in  the  treatment  of  acute  rheumatism. 
(See  Saligenin.) 

SALICYLIC  ACID  (C7H6O3  or  C6H4(OH)COOH)  occurs  natur- 
ally in  the  blossom  of  Spivcea  ulmaria  and  in  combination 
in  oil  of  winter-green.  It  is  a  white,  crystalline  body,  of 
melting-point  159°  C.,  and  can  be  easily  obtained  by 
chemical  methods  from  salicin,  coumarin,  phenol,  and 
indigotin.  It  is  little  soluble  in  cold  water,  but 
readily  soluble  in  alcohol,  ether,  and  hot  water ;  is  a  good 
antiseptic,  and  is  much  used  medicinally.  When  heated 
with  powdered  glass  or  quicklime  it  breaks  up  into  phenol 
and  carbon  dioxide. 


422  SALIGENIN—SAND 

SALIGENIN  (C7H8O2)  (o.  Hydroxy-benzyl  alcohol)  — The 
product  of  hydrolysis,  accompanying  dextrose,  as  produced 
from  the  glucoside  named  salicin  (C13H18O7). 

SALIVA  —  An  alkaline  mixture  of  fluids  secreted  by  various 
salivary  glands  (the  ducts  of  which  discharge  into  the  mouth) 
containing  an  active  principle  termed  ptyalin,  which  behaves 
as  an  enzyme  and  converts  starchy  matters  into  sugar. 

SALOL  or  PHENYL  SALICYLATE  (C13H10O3)— A  white,  crys- 
talline substance,  possessing  antiseptic  properties  and  used 
medicinally  for  internal  applications.  It  melts  at  42°  C., 
and  is  soluble  in  alcohol,  ether,  etc. 

SALSOLA — A  genus  of  seashore  plants,  rich  in  salts,  which 
when  burned,  yield  an  ash  containing  sodium  carbonate. 
(See  Barilla  and  Kelp.) 

SALT — See  Sodium  Compounds. 

SALT  CAEE— The  crude  sodium  sulphate  (Na2SO4)  as  manu- 
factured by  the  old  Leblanc  soda-process.  (See  Alkali 
Trade  and  Sodium  Compounds.) 

SALT  OF  LEMON— See  Salt  of  Sorrel. 

SALT  OF  SORREL  (Salt  of  Lemon) — An  acid  potassium  oxalate  ; 
a  mixture  of  KHC2O4  and  KHC2O4  +  H2C2O4-f  2H2O. 

SALTPETRE  (Nitre) — See  Potassium  Compounds,  p.  392. 
SALTS  (CHEMICAL)— See  Chemical  Compounds. 

SALVARSAN  ("  606  ")  (Kharsivan)  is  essentially  a  very  com- 
plex organic  compound  (di-hydroxy-diamino-arseno-benzene 
dihydrochloride  (C12H12O2N2As2,2HCl,2H2O))  containing 
arsenic  in  combination,  and  is  used  in  the  treatment  of 
syphilitic  cases ;  it  is  not,  however,  a  chemically  pure 
substance. 

SAMARIUM  (Sa) — Atomic  weight,  i5O'4.  An  extremely  rare 
chemical  element  of  the  cerium  group  (obtained  from 
didymia  from  ceria),  trivalent  in  character,  forming  salts 
such  as  the  chloride  SaCl36(H2O),  the  bromide  SaBr3,  and 
the  iodide  SaI3.  There  are  two  oxides  (Sa2O3  and  Sa4O9) ; 
the  lower  oxide  and  its  salts  are  yellow.  (See  Praseo- 
dymium.) 

SAMARSKITE — A  complex  yttrium  mineral  found  in  North 
Carolina  and  near  Miask  in  the  Ilmen  Mountains,  contain- 
ing cerium,  columbium,  tantalum,  uranium,  yttrium,  etc. 

SAND — Granular,  hard,  siliceous  material  in  pulverulent  form, 
Some  kinds  consist  nearly  entirely  of  silica.  (See  Silica.) 


SANDAL  WOOD—SAPONIFICATION  VALUE         423 

SANDAL  WOOD  (Santal  Wood)— The  dye  wood  of  the  Pterocarpus 
santalimis,  a  tree  indigenous  in  the  tropical  parts  of  Asia. 
It  is  used  in  India  for  dyeing  silk  and  cotton,  to  which  it 
imparts  reds  of  various  hues.  The  active  red  colouring 
matter  is  named  santalin  (C23H18O6(OCH3)2),  and  can  be 
obtained  in  fine  small  red  crystals  insoluble  in  water,  but 
soluble  in  alcohol.  Sandal-wood  oil,  distilled  by  steam 
under  pressure,  from  the  wood  of  the  East  Indian  Santahim 
album,  contains  from  90  to  96  per  cent,  santalol  (an  alcohol 
of  the  formula  C-^H^O),  and  a  terpene  named  santene, 
and  is  used  in  perfumery  and  medicinally  in  the  treatment 
of  gonorrhoea.  The  East  Indian  oils  have  a  sp.  gr.  of  from 
0*973  to  0-982  ;  optical  rotation,  -  14°  to  -21°;  and  refrac- 
tive index,  1*5023  to  1*5093.  The  West  Indian  oil  has  a 
sp.  gr.  of  0-960  to  0-976;  optical  rotation,  +18°  to  +29°; 
and  refractive  index,  1-5078  to  1-5096.  The  Western 
Australian  oil,  from  Fusanus  spicatus  R.Br.,  which  is 
related  to  the  East  Indian  tree,  has  a  sp.  gr.  of  from  0*958 
to  0-972,  optical  rotation  of  —0-25  to  —0*87,  and  refractive 
index  1*503  to  1*510. 

SANDARAGH — A  brittle,  yellow  gum-resin  of  a  faint  odour 
which  exudes  from  a  coniferous  tree  growing  in  Morocco 
and  Barbary,  named  Thuja  avticulata.  It  is  soluble  in  alcohol 
and  ether,  and  is  used  in  varnish-making,  etc. 

SANDSTONES  —  Siliceous  stones  more  or  less  ferruginous  in 
character,  used  for  building  purposes. 

"SANXTAS  "  FLUID — A  product  of  the  air-oxidation  of  terpenes 
in  the  presence  of  water,  containing  hydrogen  dioxide, 
thymol,  and  some  soluble  resinous  substances ;  used  as  a 
non-poisonous  oxidizing  and  bleaching  agent,  antiseptic 
and  disinfectant. 

SANTONINE  is  a  crystalline  substance  obtained  from  worm- 
seed  (Semen  contra,  etc.),  and  about  i  per  cent,  has  been 
found  present  in  the  leaves  of  Artemesia  brentfolia,  which 
grows  in  Cashmir  and  Western  Thibet.  It  is  insoluble  in 
cold  water,  somewhat  soluble  in  hot  water,  very  soluble 
in  hot  alcohol,  and  is  a  useful  remedy  for  worms  in  children, 
but  has  no  destructive  value  against  tape  or  thread  worm. 

SAPONIFICATION— A  term  given  to  the  hydrolytic  chemical 
action  whereby  fats  and  oils  containing  glycerides  are 
converted  into  soaps.  (See  Esters,  Fats,  and  Soaps.) 

SAPONIFICATION  VALUE  indicates  the  number  of  milli- 
grammes of  potassium  hydroxide  required  for  the  complete 
saponification  of  i  gramme  of  an  oil  or  fat. 


424  SAPONIN— SASSAFRAS  OIL 

SAPONIN  (formula  sometimes  given  as  C32H52Oir) — A  nearly 
white  inodorous  glucoside  of  great  foaming  power. 
It  is  a  constituent  of  common  soapwort,  Sarsaparilla 
quillaya,  and  alfalfa  (lucerne  hay),  and  otherwise  widely 
diffused  in  the  vegetable  kingdom.  Its  dust  excites  sneez- 
ing, and  when  dissolved  in  water  and  agitated,  it  makes  a 
frothy  solution  which  is  used  as  a  foam-producer  in  the 
preparation  of  beverages,  and  for  making  emulsions  with 
oils,  etc.  Commercial  saponin  is  said  to  contain  quillajic 
acid  (C19H30010).  (See  Quillaya.) 

The  saponin  occurring  in  lucerne  is  stated  to  have  the 
composition  C27H37O16N,  and  is  poisonous  to  fish,  not  by 
the  exercise  of  any  special  toxic  effect,  but  by  preventing 
the  diffusion  of  air  into  the  water. 

The  weak  acidic  nature  of  saponin  is  due  to  the  presence 
of  quillajic  acid,  which  on  boiling  with  weak  acids  is  split 
up  into  glucose  and  insoluble  quillajic  sapongenin — 

2C19H30010  +  8H20  =  4C6H1206  +  C14H2804. 

Saponins  from  quillaya  bark  yield  about  31*1  per  cent, 
sapogenin,  and  they  are  stated  to  consist  of  one-third 
quillajic  acid  and  two-thirds  of  a  body  named  sapotoxin. 

SAPPHIRE— See  Aluminium. 

SAPROPHYTES — Minute  organisms,  including  yeast  cells  and 
various  bacteria,  capable  of  inducing  processes  of  fermen- 
tation. 

SARCINE  or  HYPOXANTfflNE  (C5H4N4O)— A  weak  basic 
body  occurring  in  muscular  flesh  and  nearly  related  to 
xanthine  (CgH4N4O2).  Both  substances  are  chemically 
related  to  uric  acid. 

SARCOSINE  (C3H7NO2)— A  weak  base  obtained  together 
with  urea,  by  the  action  of  baryta  water  on  creatine — 

C4HUN303  =  C3H7N02  +  CH4N20  (urea). 

SARDINE  OIL— See  Fish  Oils. 

SARSAPARILLA-ROOT  (Smilax  sarsaparilla,  etc.)— Contains, 
besides  gum  and  starch,  a  peculiar  substance  known  under 
several  names,  amongst  others,  sarsaparillin,  which  can  be 
obtained  in  a  crystalline  form  from  an  alcoholic  extract  of 
the  root.  It  is  very  soluble  in  water  and  a  decoction  of  the 
root  is  used  in  medicine  and  in  compounding  what  is  known 
as  a  "  soft  drink  "  in  the  United  States  of  America. 

SASSAFRAS  OIL — A  yellowish  volatile  oil  distilled  from  the 
bark  and  root  of  Sassafras  officinale  L.,  having  an  odour  like 
that  of  fennel  oil.  It  has  a  sp.  gr.  of  1*065  to  I<095> 


SASSAFRAS  OIL—SCALES 


425 


SASSAFRAS  OIL  (Continued)— 

optical  rotation  +  i  to  +  4.  It  is  soluble  in  alcohol  and 
ether,  contains  safrol,  eugenol,  camphor,  pinene,  and  phellan- 
drene,  and  is  used  in  perfumery  and  medicine.  (See  Safrol.) 

SATINSPAR — A  fibrous  form  of  gypsum  (calcium  sulphate). 

SATURATED  COMPOUNDS  are  those  in  which  there  are  no 
unsatisfied  affinities — for  example,  the  normal  hydro- 
carbons of  which  methane  (CH4)  is  typical.  Methane  is  a 
saturated  body,  the  tetravalency  of  carbon  being  fully 
satisfied  by  combination  with  four  atoms  of  hydrogen. 
Again,  phosphoric  pentoxide  (P2O5)  is  a  saturated  body, 
the  2  atoms  of  phosphorus  (which  is  pentavalent)  being 
satisfied  by  combination  with  5  atoms  of  divalent  oxygen. 
(See  Unsaturated  Compounds.) 

SATURATION — The  maximum  degree  to  which  a  liquid  can 
hold  a  solid  in  solution  at  any  given  temperature. 

Many  substances  are  more  soluble  in  hot  liquids  than  in 
cold  ones,  and  such  hot  solutions  as  they  cool  down  to  the 
ordinary  temperature  throw  down  or  can  be  caused  to 
deposit  the  excess  of  the  dissolved  body.  (See  Crystalliza- 
tion and  Solution.) 

SAVIN  OIL — A  nearly  colourless,  essential  oil  of  sp/gr.  0*91 
to  0*93  and  optical  rotation  +40°  to  +60°;  soluble  in 
alcohol  and  ether ;  distilled  from  the  twigs  and  leaves  of 
Junipevus  sabina  of  Northern  Asia  and  North  America. 

SCALES  (Balances)  for 
the  determination  of 
weights  in  chemical 
operations  are  made 
of  great  variety  and 
some  of  extreme  deli- 
cacy. The  illustra- 
tion is  that  of  one  of 
Oertling's  balances, 
carrying  up  to  200 
grammes ;  the  beam 
turning  with  0*1  milli- 
gramme. 

A  new  instrument, 
named  the  "  Micro- 
scale,"  is  stated  to 
have  been  recently 
introduced  which  will 
register  weights  as 
small  as  three-millionths  of  a  milligramme. 


426  SCAMMONY— SEA  WEEDS 

SCAMMONY — A  purgative  gum-resin  produced  by  two  species 
of  convolvulus  (Scamnionium)  which  grow  in  Asia  Minor  and 
Syria.  The  active  principle  is  a  substance  of  glucoside 
character  resembling  jalapin. 

SCANDIUM  (Sc) — Atomic  weight,  44-1.  A  member  of  the 
cerium  group  and  one  of  the  rarest  chemical  elements; 
it  is  trivalent  and  forms  the  usual  salts,  including  a 
colourless  oxide  (Sc2O3),  bromide  (ScBr3,3H2O),  nitrate 
(Sc(N03)3.4H20),  and  sulphate  (Sc2(SO4)36H2O).  The 
salts  are  colourless  and  soluble  in  water.  Its  discovery 
was  predicted  from  a  study  of  the  periodic  law  of  elements. 
(See  p.  173.) 

SCAPOLITE — A  natural  silicate  of  aluminium  and  calcium. 

SOHEELE'S  GREEN— Copper  hydrogen  arsenite  (CuHAsO3), 
an  amorphous  pulverulent  pigment. 

SOHEELITE— Natural  calcium  tungstate  (CaWO4),  found  in 
Arizona,  Montana,  New  Mexico,  and  other  United  States 
— an  important  source  of  the  metal  tungsten. 

SCHWEINFUET  GREEN— See  Paris  Green. 

SEAL  OIL— See  Fish  Oils. 

SEALING  WAX— A  mixture  made  by  heating  together  shellac, 
Venice  turpentine,  and  vermilion  (mercuric  sulphide) ; 
another  mixture  is  that  of  beeswax  and  rosin.  Rosin 
(colophony)  is  often  substituted  in  part  for  shellac,  and 
various  mineral  colouring  matters  are  used  in  place  of 
vermilion  according  to  the  desired  colour ;  for  white  waxes 
basic  nitrate  of  bismuth  is  used,  giving  a  product  of  a 
beautiful  white  enamel-like  brilliancy. 

SEA-WATER— See  Water. 

SEAWEEDS — There  are  many  species  and  abundant  quantities, 
some  of  which  are  of  considerable  interest  from  a  chemical 
point  of  view.  Some  kinds  are  burned  for  the  sake  of 
their  alkaline  ash  and  as  a  source  of  bromine  and  iodine, 
and  others  are  used  as  articles  of  food  and  as  fertilizing 
agents  on  account  of  the  high  percentage  of  nitrogen  they 
contain.  The  ordinary  sea-wrack  is  also  said  to  be  service- 
able for  the  production  of  a  good  paper  pulp,  but  this  has 
been  contradicted. 

The  amount  of  ash  varies  from  177  per  cent,  in  F.  sercatits 
to  52-37  per  cent,  in  the  roots  of  L.  hyperboria. 

Laminaria  sacckarina  contains  mannite  and  is  largely  used 
as  food  in  China  and  Japan.  Varec  or  vraic  is  greatly  appreci- 
ated in  the  Channel  Islands  as  a  valuable  fertilizer,  and  duft- 
weed  is  extensively  used  in  Ireland  as  a  dressing  for  potatoes. 


SEA  WEEDS— SELENI UM  427 

SEAWEEDS  (Continued)— 

Rhodymenia palmata  (dulse)  and  Alaria  esculanta  (murlins) 
are  both  used  as  food  in  the  Scottish  Highlands  and  Ireland. 

Chondrus  cvispus  (carrageen,  or  Irish  moss)  is  sometimes 
used  by  painters  instead  of  size,  also  for  making  jellies  and 
mucilage. 

Gracilaria  lichenoides  (Ceylon  or  edible  moss)  is  found  in 
the  Indian  Archipelago  and  China  and,  together  with 
Encheuma  spinosum,  is  used  for  the  preparation  of  nutrient 
jelly  in  bacteriological  research,  also  for  gumming  silks, 
paper,  etc.,  and  for  making  soups. 

The  protein  content  of  seaweeds  varies  from  9-28  per 
cent,  in  Chondrus  crispus  to  29*06  per  cent,  in  Porphym 
laciniata,  and  the  nitrogen  content  from  1*485  to  4*65  per 
cent,  both  calculated  on  the  dry  matter. 

Seaweeds  contain  large  proportions  of  gelatinous  sub- 
stances from  which  nutritive  jellies  can  be  made,  and  a 
material  prepared  from  them,  is  used  to  some  extent  as  a 
substitute  for  horn,  shell,  whalebone,  etc.  A  new  crystalline 
sugar  named  flovidose  has  been  recently  obtained  as  a  hydro- 
lytic  product  from  the  mucilaginous  substance  formed  by 
boiling  seaweed  in  water.  (See  Agar-Agar,  Algin,  Barilla, 
Kelp,  and  Salsola.) 

SELENITE— A  native  hydrated  calcium  sulphate.  (See  Calcium.) 

SELENIUM  (Se)  and  its  Compounds— Atomic  weight,  79-2 ; 
melting-point,  217°  C. ;  boiling-point,  690°  C.  An  element 
nearly  resembling  sulphur  in  its  general  properties,  found 
in  its  free  state ;  also  in  combination  with  other  metals  in 
a  number  of  minerals,  and  as  selenide  of  sulphur  in  Swedish 
pyrites.  It  is  recovered  to  some  extent  in  the  electrolytic 
refining  of  copper  from  the  mud  that  settles  in  the  cells 
and  from  the  deposit  that  is  thrown  down  from  sulphuric 
acid  in  the  chambers  and  Glover  tower.  Like  sulphur  it 
is  allotropic,  three  varieties  at  least  being  known — viz.,  a 
vitreous  red  form,  of  sp.  gr.  4-3,  obtained  by  precipitation ; 
a  crystalline  red  form,  of  sp.  gr.  4-45,  and  the  dark  grey  or 
black  metallic  form  which  melts  at  219°  C.,  and  is  of 
sp.  gr.  4- 80.  Of  these,  the  two  first  named  are  soluble  in 
carbon  disulphide. 

The  amorphous  form  is  a  bad  conductor  of  heat  and 
electricity,  while  the  crystalline  metallic  variety  is  a  good 
conductor,  is  insoluble  in  carbon  disulphide,  and  its 
electrical  conductivity  is  increased  by  the  agency  of  light. 
Heated  in  the  air,  it  burns  with  a  blue  flame,  forming  an 
oxide  and  emitting  an  offensive  pungent  odour. 


428  SELENIUM—SERALBUMIN 

SELENIUM  (Continued) — 

Selenium  is  used  in  wireless  telephony,  electrical  and 
physical  contrivances,  in  photometry,  and  advantage  is 
taken  of  its  peculiar  electrical  conductivity  when  exposed 
to  light  in  the  construction  of  an  instrument  termed  the 
"optophone,"  by  means  of  which  the  blind  can  read  books 
through  the  agency  of  the  telephone. 

Two  oxides  apparently  exist,  but  only  the  dioxide  (SeO2) 
is  well  established,  and  is  a  white  crystalline  body  which 
can  be  sublimated,  and  dissolves  in  water  to  form  selenious 
acid  (SeH2O3)  corresponding  to  sulphurous  acid.  There  is 
also  a  selenic  acid  (SeH2O4)  corresponding  to  sulphuric  acid. 

Two  chlorides  are  known — viz.,  Se2Q2,  a  brown  oily 
compound  which  has  the  property  of  dissolving  metallic 
selenium,  and  which  is  slowly  decomposed  by  water,  and 
SeCl4,  which  is  a  white  crystalline  volatile  substance. 

Hydrogen  Selenide  (SeH2)  is  a  colourless  gas  resembling 
hydrogen  sulphide  in  its  odour  and  chemical  properties, 
obtained  by  the  action  of  an  acid  upon  a  selenide. 

The  compounds  of  selenium  resemble  those  of  tellurium 
in  most  respects. 

"SEMI-STEEL,"  S.P.M. — A  material  possessing  mechanical 
properties  intermediate  between  those  of  cast  iron  and  cast 
steel,  of  which  filter-press  plates  and  some  autoclaves  are 
constructed. 

SEMOLINA — A  farinaceous  preparation  made  from  the  hard 
grain  wheats  of  Italy,  Spain,  and  South  Russia,  containing 
a  relatively  large  amount  of  nitrogenous  material. 

SENEGAL  GUM— See  Gums. 

SENNA — A  purgative  drug  made  of  the  leaves  of  the  shrub 
Cassia  acutifolia,  or  Cassia  angustifolia,  which  grow  in  parts 
of  Abyssinia,  Barbary,  Egypt,  Tripoli,  the  East  Indies, 
and  Syria.  It  contains  a  number  of  chemical  principles, 
one  of  which  is  named  cathartin.  An  infusion  of  the 
leaves  makes  a  useful  cathartic. 

"SENSITOL"  (Green  and  Red)— Two  substances  of  dyestufi 
character  used  in  the  production  of  panchromatic  photo- 
graphs. 

SEPIA— See  Cuttle  Fish. 

SEPTIC  POISONS  —  Toxic  chemical  products  produced  by 
bacteria  as  in  wounds.  (See  Bacteria,  Microbes,  Ptomaines, 
Putrefaction,  and  Pus.) 

SERALBUMIN — Serum  albumin.  (See  Albumins,  Proteins,  and 
Serum.) 


SERPENTINE— SE  WA  GE  429 

SERPENTINE — Mineral  forms  of  hydrated  magnesium  silicate. 
Some  contain  alumina  and  others  are  free  from  that 
association. 

SERUM — That  part  of  the  blood  solution  which  remains  liquid 
after  coagulation,  the  coagulation  of  the  fibrin  entangling 
in  its  meshes  or  "  clot "  the  corpuscles  of  the  blood.  It 
contains  a  kind  of  albumin  called  seralbumin  and  some 
salts.  The  seralbumin  is  completely  separated  or  coagu- 
lated by  adding  a  little  acetic  acid  and  boiling.  The  liquid 
which  forms  in  a  blister  is  a  familiar  example  of  serum. 

SESAME  OIL — A  fatty  non-drying  oil  expressed  from  the  seeds 
of  Sesamum  ovientale  (indigenous  in  India)  containing  olein, 
stearin,  palmitin,  etc.  Its  sp.  gr.  is  0*921  to  0*925  ;  it  melts 
at  26°  to  32°  C. ;  iodine  value,  103  to  114;  saponification 
value,  1 88  to  193  ;  and  refractive  index,  1*457.  It  is  soluble 
in  ether  and  carbon  disulphide,  and  is  used  for  burning  in 
lamps,  for  soap-making,  and  as  an  article  of  food. 

SEWAGE — The  treatment  or  disposal  of  sewage  necessarily 
varies  with  the  quantity  and  quality  to  be  dealt  with. 
Small  quantities  can  be  readily  disposed  of  without  other 
treatment  by  irrigation — that  is,  distribution  over  land 
where  sufficient  is  available,  in  which  case  the  natural 
processes  of  hydrolysis,  nitrification,  and  oxidation  rapidly 
convert  the  organic  constituents  into  harmless  and  vegeto- 
nutrifying  products. 

In  moderate- sized  areas,  as  in  all  large  ones,  water  is 
employed  as  the  collecting  carrier,  and  in  these  cases,  after 
sedimentation  in  collecting  tanks  with  or  without  chemical 
treatment,  the  effluent  can,  as  a  rule,  be  distributed  over 
land,  or  carried  into  running  rivers  or  out  to  sea  where 
that  disposal  is  available.  The  chemical  treatment  in  such 
cases  depends  upon  the  character  of  the  sewage  and  the 
trades  refuse  that  may  form  part  of  it.  Sometimes  milk  of 
lime  is  used  ;  in  others,  ferrous  sulphate  or  sodium  man- 
ganate ;  and  in  yet  others,  powdered  coke  or  breeze  or  dried 
peat  can  be  used,  the  precipitated  sediment  being  disposed 
of  by  digging  into  land,  or  pressed  and  used  as  manurial 
dressing,  or  alternatively  carried  as  sludge,  containing  some 
85  per  cent,  water,  away  to  sea. 

For  large  towns  and  cities,  the  purification  of  sewage  has 
of  late  been  carried  out  in  two  stages,  the  first  of  which 
employs  treatment  in  what  is  known  as  the  "septic  tank," 
through  which  the  sewage  passes  slowly,  and  in  which  the 
solid  parts  fall  to  the  bottom  and  are  attacked  by  anaerobic 
organisms,  thus  being  ultimately  liquefied  or  turned  into 


430  SEWAGE— SHELLAC 

SEWAGE  (Continued)— 

gaseous  products.  In  the  second  stage,  the  dissolved 
impurities  are  disposed  of  by  oxidation,  a  process  which  is 
effected  by  passing  the  liquid  over  a  large  specially  con- 
structed filter  or  "  contact"  bed,  or  alternatively  over  land. 
Where  suitable  land  in  sufficient  quantity  is  not  available, 
the  artificial  filters  are  made  of  broken  clinker  or  coke,  in 
which  the  nitrifying  bacteria  carry  out  the  required 
purification. 

More  recently,  the  so-called  "  activated  sludge  "  process 
has  been  introduced,  in  which  the  whole  purification  is 
completed  in  a  tank  charged  with  a  quantity  of  activated 
sludge  to  serve  as  concentrated  carrier  of  the  nitrifying 
bacteria  upon  which  the  purification  is  dependent,  the 
charge  of  sewage  being  subjected  to  a  current  of  air  for 
several  days. 

After  the  bacterial  digestion  is  completed,  the  sludge  can 
be  pumped,  as  at  Birmingham,  over  shallow  ash-beds,  when 
it  readily  parts  with  its  water  by  filtration,  without  offence. 

It  is  stated  that  when  crude  sewage  is  passed  through  a 
filter  bed  of  straw,  the  soluble  nitrogen  compounds  are 
removed  from  it,  so  that  the  effluent  becomes  comparatively 
harmless,  and  the  straw  itself  is  thus  converted  into  a 
valuable  manure.  (See  Microbes  and  Nitrification.) 

SHALE— A  fine-grained  rock  of  silt  or  clay  with  a  cleavage 
•  like  that  of  slate.     It  occurs  in  quantity  in  Scotland  and 
elsewhere   and  is  often  of  bituminous  or   petroleum   oil- 
bearing  character.     Deposits  have  recently  been  found  in 
Derbyshire,  Norfolk  and  Notts. 

SHALE  OIL — A  sort  of  petroleum  oil  obtained  by  destructive 
distillation  of  shale  (schist)  found  as  a  natural  deposit  in 
Scotland  and  elsewhere,  ammonium  sulphate  being  obtained 
as  a  by-product.  (See  Petroleum  and  Naphtha.) 

SHARK  OIL— See  Fish  Oils. 

SHEA  BUTTER — A  greenish-white  solid  vegetable  fat  from 
the  nuts  of  Bassia  parkii  (West  Africa),  containing  oleic 
and  stearic  acids.  It  has  a  sp.  gr.  of  0-9175,  a  saponifica- 
tion  value  of  179  to  192,  and  an  iodine  value  of  56-6. 

SHELLAC — "  Stick  lac  "  is  the  lac  insect  (Coccus  lacca) — which 
abounds  in  the  forests  of  Assam — and  the  resinous  covering 
which  it  forms  on  the  branches  of  the  trees  upon  which  it 
is  found.  From  it,  is  prepared  "seed  lac" — that  is,  lac 
from  which  the  wood  has  been  removed.  Lac  dye  is  the 
colouring  matter  of  the  insect,  and  shellac  is  the  resin  pre- 


SHELLA  C—  SILICON  431 

SHELLAC  (Continued)— 

pared  by  melting  and  straining.  Shellac  is  used  in  leather- 
dressing  and  making  varnishes  and  sealing  wax.  (See 
Lacquer  and  Sealing  Wax.) 

SICCATIVES  —  Agents  which  promote  drying,  more  particularly 
applied  to  so-called  "  driers  "  used  in  connection  with 
varnishes,  oils,  and  paints,  such  as  manganese  borate  and 
manganese  resinate.  (See  Linseed  Oil,  Paints,  and 
Varnishes.) 

SIDERITE  (Spathic  Iron  Ore)  —  A  mineral  carbonate  of  copper 
(FeCO3). 

SIENNA  —  A  yellowish  clay  coloured  by  metallic  oxides  (iron 
and  manganese),  used  as  a  pigment. 

SILAGE  —  A  fermentation  product  used  as  cattle  food,  made 
from  green  fodder  (such  as  oats  and  tares,  grass  and  maize), 
which  is  cut  up  and  stored  in  such  wise  that  acetic  acid  is 
produced  and  acts  as  a  preservative. 

SILICA  —  See  Clays,  Silicon,  and  Zeolites. 

SILICATE  OF  SODA—  See  Silicon. 

SILICIC  ACID—  See  Silicon. 

SILICON  (Si)  and  its  Compounds—  Atomic  weight,  28  ;  melting- 
point,  1,420°  C.  Silicon  compounds  are  abundant  and 
widely  distributed  in  nature.  It  is  not  a  metal,  but  it  is 
known  both  in  the  forms  of  a  brown  powder  and  in  a 
crystalline  condition  of  metal-like  appearance.  Combined 
with  oxygen  as  silica  (SiO2),  it  is  found  in  the  forms  of 
flint,  sand,  quartz,  rock  crystal,  agate,  amethyst,  jasper,  chalcedony, 
christobalite,  and  tridymite.  In  other  combinations,  it  helps 
to  make  up*  the  composition  of  clay,  soil,  and  many  rocks. 
(See  Clay  and  Zeolites.) 

Silica  occurs  in  nature,  also,  in  combination  with  water 
(SiO23H2O)  in  the  forms  of  opals  and  kieselguhr. 

To  obtain  silicon  in  the  free  state,  several  processes  are 
available,  in  one  of  which,  a  mixture  of  potassium-silico- 
fluoride  and  metallic  potassium  is  strongly  heated,  when 
the  potassium  replaces  the  silicon  which  is  thus  set  free 
and  obtained  by  dissolving  out  the  potassium  fluoride  with 
water  : 


As  thus  prepared  it  is  a  dark  brown  amorphous  powder 
with  a  sp.  gr.  of  2'i^. 

Silicon  is  obtained  in  needle-shaped  crystalline  form  by 
fusing  a  similar  mixture  (or  replacing  the  metallic  potassium 


432  SILICON 

SILICON  (Continued)— 

with  metallic  sodium)  with  a  proportion  of  metallic  zinc, 
the  crystallized  silicon  being  deposited  on  the  zinc,  which 
can  be  subsequently  dissolved  out  by  acid  treatment.  In 
this  form,  the  silicon  is  hard  enough  to  scratch  glass,  has  a 
sp.  gr.  of  about  2-34  to  2-49,  and  is  very  insoluble  in  acids. 
Exposed  to  a  higher  temperature  in  vacuo  it  becomes  still 
denser  and  attains  a  sp.  gr.  of  3. 

Another  process  consists  in  heating  quartz  with  wood 
charcoal,  lime,  and  manganese  oxide  in  an  electric  furnace. 

Silicon  is  insoluble  in  water,  hydrochloric  and  nitric 
acids,  but  soluble  in  hydrofluoric  acid  and  alkalies. 

Two  compounds  of  silicon  with  hydrogen  are  known — 
viz.,  silicon  hydride  (SiH4),  a  colourless  gas  which  is 
decomposed  by  alkaline  hydrates,  giving  the  corresponding 
silicates  and  evolving  hydrogen — 

SiH4  +  2NaHO  +  H2O  -  SiO(NaO)2  +  4H2, 

and  liquid  silicon  hydride  (Si2H6),  a  colourless  mobile  liquid 
which  is  spontaneously  inflammable  in  the  air.  These 
compounds,  known  as  silanes,  are  obtained  by  the  action  of 
acid  on  magnesium  silicide. 

Quartz  crystals  find  uses  not  only  as  gems,  but  also  for 
certain  optical  purposes;  while  sodium  silicate  (Na2SiO3)  in 
the  form  of  solution  (water-glass),  is  largely  used  for  fire- 
proofing  fabrics,  in  making  concrete  hardeners,  as  a  filling 
for  soap,  etc.  It  is  also  sometimes  employed  for  preserving 
stone  facings  of  buildings  from  atmospheric  attack.  To 
understand  this  last-named  application,  it  may  be  explained 
that  many  stone  buildings  are  composed  of  natural  lime- 
stone (CaCO3),  and  the  carbon  dioxide  and  water  which  are 
always  present  in  the  air  have  a  destructive  solvent  action 
upon  such  facings.  (See  Calcium.)  This  can  be  prevented 
to  some  extent  by  washing  with  sodium  silicate,  as  the  silica 
enters  into  combination  with  the  calcium  of  the  limestone, 
forming  on  the  surface  a  thin  layer  or  coating  of  calcium 
silicate  which  is  not  subject  to  the  same  destructive  influence 

Water-glass  in  solution  is  also  largely  used  in  the  pre- 
servation of  eggs,  the  egg-shells  being  made  air-tight  by 
coating  their  surfaces  with  it,  thus  preventing  the  access 
of  air-borne  germs. 

Sodium  silicate  is  prepared  by  calcining  a  mixture  of 
quartz,  soda  carbonate,  and  powdered  coal,  and  extracting 
the  molten  mass  with  water,  etc. 

Silicon  Dioxide  or  Silica  (SiO2)  may  be  prepared  in  the 
laboratory  in  crystalline  form  or  as  a  white  powder  by  a 


SILICON  AND  ITS  COMPOUNDS  433 

SILICON  (Continued)— 

variety  of  methods,  as  when,  for  example,  amorphous 
silicon  is  burned  in  the  air.  It  is  fusible  in  the  oxy- 
hydrogen  flame,  when  it  melts  to  a  transparent  glass- 
like  mass.  I*t  is  insoluble  in  water,  and  the  only  acid  that 
will  dissolve  it  is  hydrofluoric  acid ;  it  is,  however,  soluble 
in  alkalies. 

When  fused  silica  is  heated  above  1,000°  C.  it  is  trans- 
formed gradually  into  christobalite — a  change  which  is 
completed  in  several  hours  after  continuing  the  heat  to 
1,500°  C.,  and  the  final  product  is  stated  to  be  probably 
tridymite. 

Quartz  begins  to  soften  at  about  1,650°  C.,  and  becomes 
a  viscous  fluid  at  1,750°  to  1,800°  C. 

Silica  is  stated  to  be  strongly  volatile  at  a  temperature 
slightly  above  its  melting-point,  and  its  use  as  a  substitute 
for  glass  is  a  developing  industry,  being  acid-proof,  abraded 
with  difficulty,  and  exhibiting  great  resistance  to  tempera- 
ture shocks.  Silica  glass  is  absolutely  insoluble  in  boiling 
water,  but  is  permeable  to  gases  at  high  temperatures,  and 
is  an  ideal  electrical  insulating  material.  (See  Vitreosil.) 

The  enormous  quantities  of  siliceous  "sinter"  deposited 
by  the  geysers  at  Rotomahama  in  New  Zealand  and  else- 
where, are  formed  by  the  action  of  atmospheric  carbon 
dioxide  upon  alkaline  silicates  held  in  solution  by  the  hot 
springs,  the  silicates  being  decomposed,  thereby  causing 
the  deposition  of  the  silica  and  the  re-formation  of  an 
alkaline  carbonate. 

Silicic  Acid  (Si(HO)4)  is  the  best-known  member  of  several 
weak  acids  which  are  formed  by  combination  of  silicon 
dioxide  with  water,  and  can  be  obtained  either  in  solution 
or  in  a  gelatinous  form,  in  both  of  which  it  behaves  as  a 
colloid.  Combinations  in  the  nature  of  silicates  form  a 
large  number  of  minerals,  many  of  which  are  very  complex 
in  composition  ;  amongst  the  more  simple  ones  may  be 
enumerated  :  serpentine,  a  magnesium  silicate  of  formula 
Mg3Si2O7;  felspar,  with  the  composition  Al2K2(Si3O8)a;  and 
pendote,  Mg2SiO4  (magnesium  silicate). 

Silicon  Fluoride  (SiF4)  is  a  colourless,  fuming  gas  pre- 
pared by  the  action  of  sulphuric  acid  upon  powdered  fluor- 
spar and  white  sand — 

2CaF2  +  2H2S04  +  Si02  =  2CaSO4  +  2H2O  +  SiF4. 

The  same  compound  is  formed  direct  by  bringing  silicon 
into    contact    with    fluorine    when    it    takes    fire.      The 

28 


434  SILICON-SILK 

SILICON  (Continued)— 

gas  can  be  liquefied  to  a  clear  colourless  state,  and  when 
brought  into  contact  with  water,  decomposition  takes 
place,  dibasic  silicic  acid  being  precipitated  as  a  gelatinous 
mass  accompanied  with  hydrofluosilicic  acid  in  solution — 

3SiF4  +  3H2O  -  2H2SiF6  +  H2SiO3. 

Hydrofluosilicic  Acid  (H2SiF6)  can  also  be  obtained  as  a 
colourless  fuming  liquid  by  distilling  the  gaseous  silicon 
tetrafluoride  with  water.  It  is  very  corrosive  and  is 
employed  in  the  ceramic  industries  and  in  making  concrete 
floors  and  certain  technical  paints. 

Silicon  Tetrachloride  (SiCl4)  is  produced  when  silicon  is 
strongly  heated  in  a  current  of  chlorine.  The  silicon  burns 
and  the  tetrachloride  is  formed  direct ;  or  it  can  be  made  by 
passing  chlorine  gas  over  a  mixture  of  silica  and  carbon 
(silicon  carbide)  in  an  electric  furnace,  when  the  following 
change  takes  place  : 

SiO2  +  2C  +  2C12  =  2CO  +  SiCl4 

—that  is  to  say,  the  tetrachloride  is  produced,  attended  with 
the  formation  of  carbon  monoxide.  The  gas  can  be  con- 
densed by  cooling  and  is  then  a  colourless  liquid  which 
fumes  in  the  air,  and  is  decomposed  by  water  into  silicic 
and  hydrochloric  acids.  It  was  used  in  the  Great  War  for 
producing  smoke  screens. 

Silicon  unites  with  aluminium,  iron,  zinc,  copper,  calcium, 
magnesium,  and  some  other  metals,  forming  compounds 
named  silicides.  It  also  unites  with  carbon  to  form  the 
hard  crystalline  substance  named  carbonmdum,  and  enters 
fundamentally  into  the  composition  of  various  kinds  of 
glass  which  are,  in  reality,  insoluble  compound  silicates. 

Silicon  bronze  is  an  alloy  of  silicon,  copper,  and  tin  used 
for  telegraph  and  telephone  wires. 

Silicon  acts  as  a  substitute  for  carbon  in  many  organic 
compounds,  and  among  these  are  tetramethyl  silicane 
or  silicon  methyl  (Si(CH3)4),  a  mobile  liquid  of  light 
nature,  and  tetra-ethyl  silicane  or  silicon  ethyl  (Si(C2H5)4), 
both  of  which  burn  with  a  bright  cloud  and  emit  white 
clouds  of  silica. 

(See  also  Glass,  Carborundum,  Ferro-alloys,  and  Iron.) 

SILK — The  fibrous  material  in  which  the  silkworm  envelops 
itself  before  passing  into  the  chrysalis  state,  named  sericin 


SILK— SILVER 


435 


SILK  (Continued)— 

QIC  fibroin.     This  is  coated  with  a  kind  of  wax  which  has  to 
be  removed  in  the  process  of  silk-dyeing. 

Silk  is  nearly  allied  to  but  not  absolutely  identical  with 
cellulose.  (See  Cellulose.) 

SILK  (Artificial) — All  artificial  silks  are  made  from  cellulose, 
and  so-called  mercerized  cotton  is  practically  a  simple  form 
of  artificial  silk.  (See  Mercerization.)  Thiele  silk,  which  is 
a  French  production  of  long  standing,  was  made  by 
dissolving  cellulose  in  ammoniacal  cupric  oxide  solution 
and  forcing  the  solution  through  small  holes  into  dilute 
acid,  but  the  great  advance  made  in  more  recent  times  has 
resulted  from  new  investigations.  Mercerized  cellulose 
prepared  from  wood-pulp  is  acted  upon  by  carbon  di- 
sulphide,  thus  producing  a  swollen  yellowish  mass  consisting 
of  the  sodium  salt  of  cellulose  xanthate  which  is  sub- 
sequently dissolved  in  water  and  treated  with  acid,  thus 
effecting  the  reprecipitation  of  the  cellulose  as  a  gelatinous 
mass  to  which  the  name  of  *'  viscose "  has  been  given. 
It  is  this  product,  or  that  prepared  from  other  cellulose 
fibres  by  solution  in  dilute  alkali  and  projection  through 
fine  apertures  into  a  coagulating  medium  of  sulphuric  acid 
or  other  solution,  which,  after  some  purification,  is  used  in 
the  manufacture  of  artificial  silk.  This  is  made  by  drawing 
the  coagulated  viscose  on  to  bobbins,  then  washing,  drying, 
and  weaving  as  required. 

Viscose  dries  to  a  hard,  horn-like  mass  and  is  also 
employed  as  a  substitute  for  articles  resembling  celluloid 
and  ivory,  and  when  mixed  with  zinc  oxide  or  clay  it  makes 
a  hard  substance  called  viscoid. 

Artificial  Silk  is  stated  to  have  a  greater  affinity  for  dye- 
stuffs  than  cotton,  and  unevenness  in  shade  is  occasionally 
observed  in  the  dyed  material,  but  recent  investigations 
have  provided  a  way  for  overcoming  this  difficulty. 

SILVER  (Argentum,  Ag)  and  its  Compounds — Atomic  weight, 
108;  sp.  gr.,  10-5;  melting-point,  960-5°  C.  Silver  occurs  in 
nature  in  the  metallic  state  and  in  combination  in  a  number  of 
minerals,  including  argentite  or  silver  glance  (as  silver  sulphide 
(Ag2S)),  in  horn  silver  (as  chloride  (AgCl)),  and  as  silver 
sulphide  associated  with  other  metallic  sulphides  mpyrargyrite 
(Ag3SbS3),  stephanite  (Ag5SbS4),  and  proustite  (Ag3AsS3). 
The  world's  supply  comes  from  the  United  States  of 
America,  Canada,  Mexico,  South  America,  and  Japan. 

To  obtain  metallic  silver  from  galena  containing  it,  resort 
is  had  to  the  process  described  as  cupellation,  which  depends 


436  SILVER  AND  ITS  COMPOUNDS 

SILVER  (Continued}— 

upon  the  fact  that  the  silver  can  be  concentrated  into  a 
small  portion  of  lead  by  crystallization,  and  then  the 
mixture  is  exposed  to  a  strong  blast  of  air,  thus  oxidizing 
the  lead  into  litharge  (PbO),  which  fuses  and  runs  away 
or  is  absorbed  by  the  porous  bed  of  the  furnace,  leaving  the 
silver  behind.  The  furnace  bed  is  made  of  bone  ash  so  as 
to  be  absorbent,  and  is  known  as  a  cupel. 

The  crude  silver  as  prepared  fromi  its  sources,  is  purified 
in  another  process,  by  amalgamation  with  mercury,  followed 
by  distilling  off  the  mercury,  which  leaves  the  refined  silver 
behind;  and  there  are  a  number  of  other  methods  which 
are  adapted  to  the  several  requirements  according  to  the 
composition  of  the  ore  from  which  the  silver  has  to  be 
obtained. 

Silver  is  a  white  metal  which  is  not  acted  upon  by  the 
oxygen  of  the  air ;  it  is  soluble  in  nitric  acid  and  is 
tarnished  when  sulphuretted  hydrogen  is  present  in  the 
atmosphere,  due  to  the  surface  formation  of  silver  sulphide. 
Silver  articles  deliberately  coloured  in  this  way  are  com- 
monly but  erroneously  described  as  "  oxidized  "  silver. 

It  is  the  best  metallic  conductor  of  heat  and  electricity, 
very  malleable  and  ductile,  and,  alloyed  with  copper, 
it  is  largely  used  for  coinage  and  other  purposes,  including 
jewellery  and  electro-plating.  Until  recently  the  British 
standard  for  coin  was  92^  per  cent,  silver  and  7^  per  cent, 
copper,  pure  silver  being  too  soft  to  use  alone  for  this  purpose. 
(For  Electro- Plating,  see  Electricity,  p.  166.) 

Silver  forms  several  oxides  insoluble  in  water,  including 
a  black  suboxide  (Ag4O)  and  the  monoxide  (Ag2O),  the 
last  named  being  produced  by  the  addition  of  an'alkaline 
hydroxide  solution  to  one  of  silver  nitrate.  It  also  is 
black,  and  when  dried  and  heated  to  260°  C.  gives  off 
oxygen  and  is  reduced  to  the  metallic  state.  It  is  soluble 
in  strong  ammonia,  and  the  solution,  on  standing,  deposits 
black  shining  crystals  of  what  is  known  as  fulminating  silver, 
an  explosive  compound  believed  to  be  the  nitride  Ag2N. 

Silver  Chloride  (AgCl)  is  white,  and  insoluble  in  water, 
but  soluble  in  ammonia. 

Silver  Bromide  (AgBr)  is  pale  yellow  and  less  soluble  in 
ammonia,  but  is  soluble  hi  solutions  of  potassium  bromide 
and  cyanide. 

Silver  Iodide  (Agl)  is  yellowish,  still  less  soluble  in 
ammonia,  but  the  most  stable  of  the  three  halogen  com- 
pounds. 


SIL  VER—SKA  TOLE  437 

SILVER  (Continued)— 

Silver  Nitrate  (lunar  caustic)  (AgNOg)  is  made  by 
melting  the  crystals  of  that  compound  at  about  218°  C. 
It  is  the  most  important  soluble  silver  compound  as, 
apart  from  its  use  in  photography,  it  is  used  medicinally 
as  a  caustic  application,  also  in  silver  plating  and  in  the 
manufacture  of  an  indelible  ink  for  marking  linen,  etc. 
It  crystallizes  in  large  rhombic  tables,  is  very  soluble  in 
water,  is  decomposed  at  a  red  heat,  giving  off  oxygen, 
and  is  wholly  decomposed  at  a  higher  temperature,  leaving 
the  metal  as  a  residue. 

Silver  Sulphide  (Ag2S)  is  formed  as  a  black  precipitate 
by  passing  hydrogen  sulphide  gas  through  solutions  of 
silver  salts,  and  it  occurs  naturally  in  the  form  of  silver 
glance.  It  is  used  in  inlaying  in  niello  metal  work. 

Silver  Potassium  Cyanide  (KAg(CN)2)  is  a  white  crystal- 
line, soluble  in  water  and  used  in  silver  plating,  etc. 

Many  of  the  silver  compounds  are  used  in  photography, 
and  as  the  chloride  is  soluble  in  sodium  hyposulphite,  that 
reagent  is  extensively  used  for  "  fixing  "  purposes — that  is, 
dissolving  out  the  silver  compound  that  has  not  been 
decomposed  by  the  actinic  rays. 

SINAPINE — An  organic  base  of  alkaloidal  character  contained 
in  white  mustard  seed.  (See  Mustard.) 

SINTER — Incrustation  on  rocks,  etc.,  deposited  from  mineral 
waters.  (See  Silicon,  p.  433.) 

SIPHONS — Appliances  for  drawing  off  (siphoning)  fluids  from 
one  vessel  to  another. 

SISAL  HEMP  (for  twine-making,  etc.)  is  obtained  from  a  plant 
(Agave  rigida)  growing  in  Central  America  and  the  West 
Indies  and  now  cultivated  on  an  extensive  scale  in  some 
parts  of  East  Africa,  and  is  said  to  be  more  popular  with 
spinners  than  Mexican  henequen. 

Ordinary  hemp  comes  from  the  plant  Cannabis  sativa,  a 
native  of  India,  and  is  cultivated  extensively  in  other 
countries.  (See  Hempseed  Oil.) 

SIZE — A  gelatinous  body,  being  an  undried  form  of  glue, 
prepared  as  a  jelly  from  the  third  extraction  of  bones  in 
the  making  of  glue. 

SKATOLE  (C9H9N) — A  crystalline  substance  found  amongst 
the  products  of  the  putrefactive  decay  of  albuminous  sub- 
stances, also  in  faeces ;  it  melts  at  95°  C. 


SLAG 

SLAG  (Basic  Slag) — Cinder  from  blast-furnaces  consisting 
largely  of  silicates  of  calcium  and  aluminium,  containing 
also  phosphates  in  considerable  proportion.  When  reduced 
to  powder  it  is  largely  used  as  a  phosphatic  fertilizing  material 
for  agricultural  purposes  and  in  making  cement.  (See 
Iron.) 

The  phosphide  of  iron  (Fe2P)  representing  the  state  of 
combination  in  which  the  phosphorus  exists  in  molten  iron 
is  oxidized  by  reactions  of  the  type — 

5Fe3O4  +  2P  =  15FeO  +  P2O5 
and 

5Fe3O4  +  8P  =  15Fe  +  4P2O5. 

The  P2O5  may  combine' with  FeO  to  form  Fe3(PO4)2,  but 
as  this  is  unstable  in  the  presence  of  a  large  excess  of  iron, 
a  reaction  such  as 

Fe3(PO4)2  +  1 1  Fe  =  8FeO  +  2Fe3P 

results,  and  it  is  in  consequence  of  this  change,  that  the  acid 
process  of  steel -making  is  unable  to  remove  phosphorus. 
In  the  basic  process,  the  presence  of  lime  causes  the 
formation  of  phosphate  by  .the  change  indicated  by  the 
reaction — 

Fe3(PO4)2  +  4CaO  =  Ca4P2O9  +  3FeO. 

The  calcium  phosphate  thus  formed  is  only  feebly  attacked 
by  the  metallic  iron,  but  manganese  and  carbon  act  more 
vigorously  and  cause  the  phosphoric  acid  to  be  reduced  and 
the  metal  to  be  rephosphorized,  a  tendency  which  is  re- 
strained, however,  by  maintaining  a  certain  concentration 
of  ferrous  oxide. 

The  high  reputation  basic  slag  from  the  Bessemer 
process  has  acquired  for  the  improvement  of  poor  pastures 
is  said  to  be  indirect  and  to  result  from  a  stimulation  of  the 
white  clover,  although  it  is  not  definitely  known  whether 
the  action  of  the  phosphate  is  on  the  clover-plant  or  on  the 
nodule  organism.  It  contains  from  16  to  20  per  cent, 
phosphoric  acid  in  combination  with  lime,  etc.  The  new 
so-called  basic,  open-hearth  process  gives  two  qualities  of 
slag,  both  of  which  are  poorer  in  phosphates  and  contain 
on  average  from  9  to  13  per  cent,  phosphoric  acid  in 
combination.  One  is  made  by  a  process  involving  the 
use  of  calcium  fluoride,  and  is  consequently  less  soluble 
than  the  other,  whereas  that  made  without  fluorspar  is  as 
effective  as  the  old  Bessemer  slag  when  compared  on  the 


SLAG— SOAPS  439 

SLAG  (Continued)— 

basis  of  equal  amounts  of  phosphorus  content.  The 
demand  for  basic  slag  is  so  great  that  it  is  computed 
British  agriculturists  could  absorb  as  much  as  three  to  four 
hundred  thousands  of  tons  per  annum  if  available. 

In  certain  experiments  made  at  Cockle  Park,  untreated 
pasture  yielded  about  20  Ib.  of  lean  meat  per  acre  per 
annum,  whereas  after  treatment  with  slag  the  yield  rose  to 
105  Ib.  of  meat  per  acre.  Moreover,  after  eleven  years' 
treatment  with  basic  slag  the  percentage  of  nitrogen  in  the 
soil  increased  from  0-185  to  0-286  per  cent. — a  gain  of  about 
850  Ib.  per  acre. 

The  slag  preferred  for  agricultural  dressing  is  ground 
sufficiently  fine  to  allow  80  per  cent,  of  the  total  weight  to 
pass  through  a  sieve  having  10,000  apertures  to  the  square 
inch.  The  value  of  commercial  deliveries  in  the  past,  has 
not  been  based  upon  the  phosphate  total  content,  but  upon 
that  portion  of  it  which  is  soluble  in  a  2  per  cent,  solution 
of  citric  acid  under  certain  prescribed  conditions  formulated 
by  the  Board  of  Agriculture.  It  has,  however,  been 
recently  pointed  out  that  the  slag  varies  in  quality  so 
enormously  that  the  proportion  of  phosphate  dissolved  by 
2  per  cent,  citric  acid  solution  also  greatly  varies — viz., 
from  about  6  to  29  per  cent. — showing  that  this  test  and 
the  total  phosphate  content  is  not  sufficient  to  afford 
reliable  information  of  the  fertilizing  values  of  different 
qualities  of  basic  slag.  The  essential  fertilizing  con- 
stituents of  slags  is  a  matter  of  some  doubt,  and  by  some 
it  is  considered  likely  that  the  silico-phosphates  are  the 
most  valuable. 

The  annual  output  of  slag  phosphate  in  the  United 
Kingdom  is  about  400,000  tons. 

SLAG  WOOL— See  Iron. 

SLATE — A  mineral  form  of  silicate  of  aluminium  and  mag- 
nesium— a  kind  of  argillaceous  (clay-like)  rock. 

SMALT— See  Cobalt. 

SMALTINE— See  Cobalt. 

SMITHSONITE — A  mineral  carbonate  of  zinc  (ZnCO3). 

SOAPS — Combinations    or   salts    of    fatty   acids   with   alkali, 
including  hard,  soft,  silicated,  and  resinated  varieties. 

Hard  Soaps  are  manufactured  from  the  harder  fats,  such 
as  tallow,  palm  oil,  cocoa-nut  oil,  etc.,  with  or  without  the. 


440  SOAPS 

SOAPS  (Continued)— 

addition  of  rosin  (which  also  combines  with  alkali)  by 
boiling  with  caustic  soda  lye  of  sp.  gr.  1*05,  the  soap  being 
afterwards  "  salted  "  out  by  the  addition  of  common  salt, 
which  renders  it  insoluble.  After  withdrawing  the  spent 
lye  from  which  glycerine  is  obtained  (see  p.  231),  the  soap 
is  solidified  in  rectangular  iron  frames  and  after  hardening 
(drying)  by  keeping,  is  cut  up  into  slabs  and  bars  by  means 
of  wires. 

Silicated  Soaps  are  otherwise  ordinary  soaps  into  which 
a  proportion  of  an  alkaline  silicate  is  introduced,  as  these 
substances,  like  soaps,  have  the  property  of  liberating 
alkali  when  dissolved  in  water.  The  sodium  silicate  is 
prepared  by  fluxing  clean  sand  and  soda  ash  (sodium 
carbonate)  in  certain  proportions,  and  for  the  potassium 
silicate  used  for  incorporation  with  soft  soaps,  potassium 
carbonate  is  substituted  for  the  soda  ash. 

Mottled  Soaps  are  produced  by  adding  to  the  nearly  finished 
hard  soap  mass,  crude  soda  liquor  containing  some  sodium 
sulphide,  from  a  water-pot.  In  this  way,  any  iron  that  may 
be  present  in  the  soap  combines  with  the  sulphur  of  the 
sulphide  to  form  iron  sulphide,  which  makes  its  appearance 
in  streaks  or  veins.  In  some  cases,  a  little  ferrous  sulphate 
is  added  to  the  soap  during  the  boiling  and  this  becomes 
decomposed,  forming  first  of  all  ferrous  oxide  and  then 
ferric  oxide,  thus  mottling  the  soap  in  a  marked  degree. 

Again,  in  other  cases,  the  mottling  is  produced  by  the 
addition  of  Prussian  blue  ;  but  mottling  is  only  an  old  trade 
practice  and  serves  no  useful  purpose. 

Soft  Soaps  are  made  chiefly  from  linseed,  castor,  and 
other  seed  and  fish  oils,  tallow  or  resin  being,  at  times,  in- 
corporated in  certain  proportions  for  stiffening  purposes, 
and  potash  lye  being  used  as  the  saponifying  agent.  In 
some  cases,  the  glycerine  is  left  in  the  soap,  which  is 
heated  and  stirred  until  it  "talks,"  and  during  which 
operation  much  of  the  water  is  evaporated,  after  which 
it  is  ready  for  packing.  In  other  cases  the  glycerine  is 
removed  from  the  soap  by  chemical  processes. 

Toilet  Soaps  are  made  of  hard  soap  suitably  moulded  into 
tablets,  and  may  be  perfumed  or  impregnated  with  any 
desired  substance.  The  transparent  character  of  certain 
varieties  is  obtained  by  the  addition  of  sugar,  honey,  or 
alcohol. 

Hard   soaps   contain   from    u    to   69  per   cent,   of  fat 


SOAPS— «  SO  DA -OLE  IN  "  441 

SOAPS  (Continued)— 

acids,  the  best  qualities  containing  about  62  per  cent,  and 
upwards. 

Soft  soaps  contain  from  40  to  45  per  cent,  fat  acids,  and 
good  toilet  soaps  from  60  to  70  per  cent. 

From  a  recent  investigation  P.  J.  Fryer  concludes  that 
"  the  velocity  of  saponification  of  oils  and  fats,  from  the 
point  of  view  of  the  amount  of  free  alkali  removed  from 
the  reacting  solution,  is  in  inverse  ratio  to  the  saponification 
equivalent  or  to  the  mean  molecular  weight  of  fatty  acids" 
of  their  glycerides. 

The  detergent  action  of  soap  is  chiefly  attributable  to  its 
power  of  dissolving  and  emulsifying  oil  (including  paraffin 
oil),  thus  producing  soluble  compounds  or  emulsified 
mixtures  readily  removable  by  water. 

Soap  solutions  possess  a  high  degree  of  electrical  con- 
ductivity both  in  dilute  and  concentrated  solutions. 

SOAP-STONE  (steatite — French  chalk)  is  composed  chiefly  of 
talc  or  a  native  form  of  magnesium  silicate. 

SOAPWORT— See  Saponin. 

SOBREROL  (C10H16(OH)2) — A  crystalline  compound  formed 
when  pinene  (a  terpene)  is  left  exposed  to  sunlight  in 
contact  with  air  and  water. 

SODA— See  Sodium. 

SOD  AMIDE  (NH2Na)  is  obtained  by  passing  dry  ammonia  gas 
over  molten  sodium  in  the  absence  of  air.  It  is  a  powerful 
dehydrating  agent,  which  finds  use  is  the  synthetic  produc- 
tion of  indigo  from  aniline. 

SODA  ASH— Crude  sodium  carbonate. 

SODA-LIME — A  laboratory  reagent  sometimes  used  in  making 
nitrogen  determinations  in  organic  analyses,  and  employed 
for  the  absorption  of  various  acid  gases,  such  as  phosgene,  in 
military  operations.  It  consists  of  caustic  soda  and  quick- 
lime, and  is  made  by  moistening  a  mixture  of  the  two 
ingredients  with  a  solution  of  caustic  soda  and  drying  the 
mixture. 

SODA  NITRE— See  Sodium. 

"SODA-OLEIN" — A  commercial  preparation  in  the  nature  of 
sulphonated  castor  oil. 


442  SODIUM  AND  ITS  COMPOUNDS 

SODIUM  (Natrium,  Na)  and  its  Compounds  —  Atomic  weight,  23  ; 
sp.  gr.,  o'97  ;  melting-point,  97*5°  C.  Sodium,  like  potas- 
sium, is  one  of  the  alkali  group  of  metals,  and  its  chloride 
is  best  known  as  a  constituent  of  sea-  water,  which  contains 
an  average  of  about  28  parts  per  1,000. 

Sodium  chloride  (NaCl),  or  common  salt,  also  occurs 
naturally  in  large  deposits  in  Cheshire,  Lancashire,  and  else- 
where, whilst  sodium  nitrate  (NaNO3)  is  the  principal 
constituent  of  caliche  or  soda  nitre,  which  is  found  in  large 
quantities  in  Chili  and  Peru  and  which  is  exported  to  the 
extent  of  some  two  million  tons  annually,  having  great 
value  as  a  fertilizing  agent  on  account  of  its  richness  in 
nitrogen. 

In  the  purified  state,  salt  forms  a  very  valuable  food  for 
men  and  animals. 

At  Lake  Magadi  in  British  East  Africa  there  exists  a 
remarkable  deposit  of  natural  crystalline  sesquicarbonate 
of  soda  of  vast  extent,  stated  to  contain  200  million  tons 
of  soda  free  from  sulphur  impurities.  It  is  stated  to 
contain  sodium  salts  to  the  extent  of  40*38  per  cent,  when 
calculated  as  Na2O,  and  which  upon  the  calcined  product 
would  amount  to  58*08  per  cent.,  or  99-3  per  cent,  dry  soda 
ash  (NajjCOg). 

Metallic  sodium  is  now  made  in  large  quantity  by  the 
electrolysis  of  fused  caustic  soda  at  a  temperature  of  about 
20°  C.  above  its  melting-point,  or  by  the  electrolysis  of 
fused  sodium  chloride,  using  a  cathode  of  molten  lead,  and 
subsequent  electrolysis  of  the  sodium-lead  alloy  thus  pro- 
duced. It  is  used  largely  in  other  manufactures,  including 
that  of  indigotine  as  prepared  synthetically. 

Metallic  sodium  is  very  like  potassium  in  most  respects, 
being  soft  and  silver-white,  and  decomposing  water  with 
considerable  violence  on  being  thrown  into  it  — 


The  Na2O,  or  sodium  oxide,  thus  formed  dissolves  in  the 
excess  of  water  and  forms  sodium  hydrate  (hydroxide)  or 
caustic  soda  (NaHO)  solution. 

The  pure  oxide  is  formed  when  metallic  sodium  is 
exposed  to  dry  air  at  a  low  temperature.  It  is  white, 
amorphous,  and  has  a  great  avidity  for  water. 

Caustic  Soda  (NaHO)  is  largely  manufactured  for  use  in 
many  chemical  applications,  especially  in  the  making  of  soap, 
being  capable  of  decomposing  fats  and  oils,  thus  liberating 


SODIUM  AND  ITS  COMPOUNDS  443 

SODIUM  (Continued)— 

glycerine,  and  combining  with  the  fatty  acids  (their  other 
constituents).  (See  Soaps.) 

Much  of  the  caustic  soda  that  is  manufactured  is  still 
made  indirectly  from  common  salt  by  various  chemical 
processes,  and  in  particular  by  treatment  of  the  derived 
crude  sodium  carbonate  with  lime,  the  liquors  being  thus 
"  causticized  "  and  attended  with  the  production  of  calcium 
carbonate  as  a  by-product.  The  causticized  liquor  is  then 
evaporated  down  to  a  state  of  fusion.  An  increasingly 
large  amount,  however,  is  now  commercially  made  by 
processes  of  electrolysis  direct  from  brine  or  strong  solu- 
tion of  common  salt  (NaCl)  in  water. 

Caustic  soda  is  a  white,  highly  deliquescent,  caustic 
substance,  and  is  marketed  in  several  forms  and  of 
varying  degrees  of  purity  and  strength,  suited  to  its 
several  applications.  These  include  a  liquor  form  of 
90°  Tw.  strength  ;  solid  forms  of  from  60  to  76  per  cent. ; 
powder  form  of  from  77  to  78  per  cent,  (in  terms  of 
Na2O) ;  a  crude  form  containing  from  40  to  42  per  cent. ; 
and  a  still  cruder  form  styled  "  bottoms." 

Sodium  Peroxide  (Na2O2)  results  from  the  burning  of 
metallic  sodium  in  oxygen.  It  is  a  nearly  white  substance 
of  considerable  commercial  importance,  owing  to  the  fact 
that  in  contact  with  water  or  dilute  acids  it  decomposes, 
yielding  hydrogen  peroxide  in  solution : 

Na202  +  2HC1  =  2NaCl  +  H2O2. 

It  is  consequently  used  as  a  bleaching  agent  for  wool, 
silk,  yarn,  and  various  fibres,  and  in  the  straw-hat  and 
other  industries.  It  is  commercially  made  by  passing 
purified  dry  air  over  metallic  sodium  placed  on  trays  of 
aluminium  at  a  temperature  of  300°  C. 

Sodium  Carbonate  (Na2CO3)  is  extensively  used  in  glass 
manufacture,  and  is  the  basis  of  washing-soda  (soda 
crystals,  Na2CO3ioH2O),  which  is  so  largely  employed 
for  detergent  and  cleansing  purposes,,  and  this  compound 
in  its  several  commercial  forms  is  also  obtained  from 
common  salt  by  a  number  of  chemical  processes. 

When  common  salt  (NaCl)  is  subjected  to  the  action  of 
strong  sulphuric  acid  at  a  temperature  of  about  120°  F.,  it 
is  resolved  into  sodium  sulphate  and  hydrochloric  acid 
gas  which  can  be  subsequently  condensed  and  dissolved 


444  SODIUM  AND  ITS  COMPOUNDS 

SODIUM  (Continue^— 

by  the  action  of  water.  In  the  so-called  Leblanc  process, 
crude  sodium  carbonate  is  made  by  furnacing  sodium 
sulphate  (produced  as  above  described)  with  chalk  or 
limestone  or  lime  and  small  coal,  when  a  number  of 
chemical  changes  take  place  of  which  a  general  view  is 
indicated  by  the  equation  : 

Na2SO4  +  2C  +  CaCO3  =  CaS  +  2CO2  +  Na2CO3, 

calcium  sulphide  being  formed  together  with  the  carbonate 
of  sodium  which  is  afterwards  dissolved  out  of  the  fluxed 
mass  with  water  and  purified.  (See  Alkali  Trade,  p.  18.) 

Soda  crystals  effloresce  or  give  up  water  when  exposed 
to  the  air,  the  crystals  falling  to  powder  having  the  com- 
position Na2CO3H2O.  A  carbonate  can  be  obtained  in 
rhombic  crystals  by  crystallization  from  hot  solutions  with 
the  composition  Na2CO3,7H2O.  This  is  a  soluble  salt, 
100  parts  water  dissolving  59  parts  at  32*5°  C. 

Sodium  hydrogen  carbonate  or  so-called  bicarbonate 
(NaHCO3)  is  obtained  commercially  by  the  ammonia-soda 
process,  but  can  be  made  by  the  action  of  carbon  dioxide 
upon  the  ordinary  carbonate  — 

Na2CO3,  ioH20  +  CO2  =  2NaHCO3  +  9H2O. 

There  is  also  a  so-called  sesquicarbonate  of  sodium  which 
occurs  in  Egypt  and  elsewhere  as  a  natural  deposit, 
having  the  composition  expressed  by  the  formula  Na2CO3, 
2NaHC03,2H20. 

Large  quantities  of  sodium  carbonate  are  now  made  by  the 
ammonia  process,  in  which  sodium  chloride  and  hydrogen 
ammonia  carbonate  (ammonium  bicarbonate)  are  made  to 
interact  in  such  a  way  as  to  result  in  the  formation  of 
ammonium  chloride  and  hydrogen  sodium  carbonate. 

(NH4)HCO3  +  NaCl  =  NaHCO3  +  NH4C1. 

In  this  process,  a  brine  solution  is  saturated  with  ammonia 
gas,  and  the  liquid  is  then  charged  with  carbon  dioxide 
gas;  the  sodium  bicarbonate  thus  produced,  being  but 
slightly  soluble  in  cold  water,  separates  out,  and  is  con- 
verted into  the  normal  carbonate  by  calcination.  The 
ammonium  chloride,  which  is  more  soluble,  remains  in 
solution,  and  the  ammonia  is  afterwards  recovered  from 
it  by  the  action  of  lime  — 


2NH4C1  +  CaH202  -  CaCl2  +  2N  H4HO. 


SODIUM  AND  ITS  COMPOUNDS  445 

SODIUM  (Continued)— 

Sodium  carbonate  is  also  manufactured  on  a  large 
scale  by  a  process  involving  the  electrolysis  of  a  strong 
solution  of  brine  (common  salt),  which  produces  chlorine 
at  the  anode  and  generates  sodium  hydroxide  at  the 
cathode.  The  solution  of  sodium  hydroxide  can  be  evap- 
orated to  dryness,  thus  furnishing  solid  caustic  soda,  or 
made  to  encounter  a  stream  of  steam  and  carbon  dioxide, 
and  thus  converted  into  sodium  carbonate,  which  is  washed 
away  in  solution  and  concentrated  by  heat  to  the  point  of 
crystallization.  The  chlorine  generated  as  above  described 
is  utilized  in  the  manufacture  of  bleaching-powder  or  con- 
densed and  liquefied. 

Apart  from  the  uses  of  sodium  carbonate  already  noted, 
it  is  largely  employed  in  the  manufacture  of  soaps,  metal- 
lurgy, as  a  flux,  and  in  the  leather  trade. 

Sodium  Bicarbonate  is  largely  used  in  compounding  effer- 
vescent salts,  artificial  mineral  waters,  baking-powders, 
and  in  many  industries. 

Sodium  Sulphate  (Na2SO4)  is  found  naturally  in  the  form 
of  the  mineral  thenardite,  whilst  glaubevite  is  a  double  sulphate 
of  sodium  and  calcium. 

Apart  from  its  incidental  manufacture  in  the  alkali  trade 
as  so-called  salt-cake,  it  is  obtained  from  Stassfurt  salts  by 
interaction  between  magnesium  sulphate  and  sodium 
chloride — 

2NaCl  +  MgSO4  =  Na2SO4  +  MgCl2. 

It  is  a  highly  soluble  salt  which  crystallizes  with  10  mole- 
cules of  water  (Na2SO4,ioH2O),  is  efflorescent,  and  melts 
in  its  own  water  of  crystallization  when  heated  to  33°  C. 
By  more  exposure  to  the  air,  it  gradually  loses  all  its  water, 
and  is  then  known  as  "desiccated  Glauber's  salts."  It  has 
medicinal  value  as  a  purgative. 

Sodium  Hydrogen  Sulphate  (NaHSO4),  known  also  as 
"bisulphate"and  "nitre-cake,"  was  produced  on  an  immense 
scale  during  the  recent  war  as  a  by-product  in  the  manu- 
facture of  nitric  acid  which  is  generally  not  pushed  be- 
yond the  first  stage,  as  represented  (see  p.  337)  by  the 
equation 

NaN03  +  H2SO4=  NaHS04  +  HNO3, 

and  it  became  a  matter  of  considerable  importance  to 
devise  means  of  utilizing  this  residual  substance  containing 
the  equivalent  of  a  mixture  of  30  per  cent,  sulphuric  acid 


446  SODIUM  AND  ITS  COMPOUNDS 

SODIUM  (Continued)— 

and  70  per  cent,  of  sodium  sulphate.  Of  these,  there  are 
two  methods  which  may  be  here  referred  to.  In  the  one, 
ammonia  gas  is  passed  into  a  heated  solution  of  the  nitre- 
cake  containing  a  proportion  of  sulphuric  acid,  and  after 
saturation,  the  bulk  of  the  sodium  sulphate  (Na2SO4)  thus 
produced,  is  crystallized  out,  leaving  ammonium  sulphate  in 
the  mother-liquor,  from  which  it  can  be  obtained  by  crystal- 
lization or  evaporation  to  dryness.  In  other  words,  the 
acid  sodium  sulphate  (sodium  hydrogen  sulphate)  is  thus 
converted  into  the  normal  sulphate,  ammonium  sulphate 
being  simultaneously  produced — 

2NaHS04+2NH3  =  Na2S04+(NH4)2S04. 

The  other  method  consists  in  dissolving  gafsa  phosphate 
in  a  solution  of  nitre-cake,  100  parts  of  the  phosphate 
(59  per  cent,  strength)  requiring  about  184  parts  of 
the  nitre-cake  to  furnish  the  required  amount  of  SO3 ; 
44*63  parts  of  water  being  used  and  subsequently  increased 
by  a  further  10  per  cent.  The  product  thus  obtained  is  used 
as  a  fertilizer. 

Nitre-cake  was  used  during  the  war  in  grease  recovery, 
bleaching  and  dyeing,  metal  pickling,  hydrochloric  acid 
manufacture,  mineral  water  making,  as  a  flux,  and  other- 
wise to  the  total  extent  of  288,000  tons.  (See  Nitric  Acid 
and  Superphosphate  of  Lime.) 

Sodium  Bromide  (NaBr)  and  the  Iodide  (Nal),  both  of 
which  are  used  in  photography  and  medicine,  are  readily 
soluble  in  water  and  are  white  crystalline  salts  which  are 
produced  by  processes  like  those  used  for  preparing 
the  corresponding  potassium  compounds.  The  fluoride 
(NaF)  is  a  crystalline  salt  soluble  in  25  parts  of  water, 
and  the  solution  which  attacks  glass  is  used  in  etching 
and  for  other  applications.  It  is  prepared  by  neutralizing 
hydrofluoric  acid  with  sodium  carbonate. 

Sodium  Nitrate  (NaNO3)  is  easily  obtained  in  a  state  of 
purity  by  re-crystallization  from  its  crude  sources.  It  is  a 
somewhat  deliquescent  and  very  soluble  salt,  100  parts 
water  dissolving  nearly  69  parts  at  o°  C.  and  102  parts  at 
40°  C.  Apart  from  its  use  in  connection  with  the  produc- 
tion of  nitric  acid  it  is  of  value  as  a  fertilizing  agent,  a 
flux,  in  the  glass  industry,  and  for  the  production  of 
potassium  nitrate.  (See  Caliche  and  Potassium  Nitrate.) 

Sodium  Sulphites — of  which  there  are  a  number — are 
referred  to  more  particularly  elsewhere.  (See  Sulphur.) 
They  are  used  commercially  on  account  of  their  value  in 


SODIUM  AND  ITS  COMPOUNDS  447 

SODIUM  (Continued)— 

the  brewing  industry  and  as  bleaching  agents.  The  bisul- 
phate  powder  used  in  the  brewing  trade  has  a  value  in 
terms  of  SO2  (sulphur  dioxide)  of  from  60  to  62  per  cent, 
and  it  is  also  prepared  in  liquid  form  of  70°  Tw.  strength 
yielding  about  25  per  cent.  SO2  in  use. 

Sodium  Hydrosulphite  (Na2S2O4)  is  a  yellowish  white 
crystalline  substance,  soluble  in  water,  used  as  a  bleach- 
ing and  reducing  agent.  (See  "  Hydros.") 

Sodium  Hyposulphite  (Thiosulphite)  (Na2S2O35H2O), 
commonly  known  as  "  hypo,"  is  largely  used  in  photography 
as  a  "fixing  agent"  by  reason  of  its  value  as  a  solvent 
of  undecomposed  silver  salts.  (See  Sulphur  Compounds.) 

Sodium  Phosphates— Of  these,  the  chief  compound  is  the 
common  or  di-sodium  hydrogen  orthophosphate,  which  is 
prepared  commercially  by  interaction  in  solution  between 
sodium  carbonate  and  phosphoric  acid.  It  is  an  efflorescent 
crystalline  salt  of  composition  Na2HPO4,i2H2O,  which 
becomes  anhydrous  upon  heating,  and  is  used  in  compound- 
ing baking-powder.  Other  crystalline  phosphates  are 
normal  sodium  orthophosphate  (Na3PO4),  and  sodium  di- 
hydrogen  orthophosphate  (NaH2PO4). 

The  so-called  microcosmic  salt  is  a  compound  phosphate 
corresponding  to  NaH2PO4,  in  which  an  atom  of  hydrogen 
is  replaced  by  ammonium  (NaH(NH4)PO4,4H2O) ;  it 
crystallizes  with  4  molecules  of  water. 

Sodium  Pyrophosphate,  an  opaque,  crystalline,  white  salt, 
has  the  composition  Na4P2O7.6H2O,  derived  from  pyro- 
phosphoric  acid  (H2P2O7).  There  are  a  number  of  so- 
called  metaphosphates  obtained  from  metaphosphoric  acid 
(HPO3)  (or  so-called  glacial  phosphoric  acid),  including  the 
sodium  salt  NaPO3  ;  the  dimetaphosphate  is  Na2P2O6,  and 
the  trimetaphosphate  Na3P3O9. 

Sodium  Phosphites — Of  these,  there  are  two  salts,  which 
are  represented  by  the  formulae  Na2HPO3  and  NaH2PO3 
obtained  from  phosphorous  acid  (H3PO3). 

Sodium  Nitrite  (NaNO2)  is  a  stable  crystalline  salt  which 
is  produced  by  reduction  of  the  nitrate  resulting  from 
heating  above  the  fusion-point,  but  is  commercially  made 
by  an  electrolytic  process.  It  is  used  in  the  dye  industry, 
and  as  a  substitute  for  potassium  nitrite. 

Sodium  Sulphide  (Na2S)  is  a  soluble  compound  prepared 
for  commercial  purposes  in  crystalline  form  containing 


448  SODIUM  AND  ITS  COMPOUNDS 

SODIUM  (Continued)— 

30  to  32  per  cent,  and  in  that  of  a  liquid  of  60  to  62  per 
cent,  strength.  It  can  be  obtained  by  reduction  of  the 
sulphate  by  heating  with  carbon,  or  by  the  action  of 
hydrogen  sulphide  upon  caustic  soda.  It  is  used  for  deni- 
trating  artificial  silk,  as  a  depilatory  in  tanning,  etc. 

Sodium  Oxalates — The  normal  salt  (Na^CaOJ  and  the 
acid  salt  (NaHC2O4H2O)  are  both  crystalline  and  soluble 
in  water,  and  are  used  in  the  textile  industry.  The  normal 
salt  occurs  in  a  great  number  of  plants,  also  in  varech. 
The  "  salt  of  sorrel "  of  commerce  is  a  mixture  of 
the  potassium  acid  salt  KHC2O4  and  another  salt 
KHC2O4+  H2C2O42H2O. 

Sodium  Manganate  and  Permanganate — See  Manganese, 
p.  306. 

Sodium  Tannate — A  compound  of  tannic  acid  (gallo- 
tannic  acid)  with  soda. 

Sodium  Borate — See  Boron,  p.  65. 

Sodium  Perborate  (NaBO34H2O)  is  a  crystalline  salt 
prepared  by  mixing  a  3  per  cent,  solution  of  hydrogen 
dioxide  with  a  saturated  solution  of  borax  in  alkaline 
solution  at  a  low  temperature,  when  it  is  deposited  in 
crystalline  form  on  standing.  It  is  a  dangerous  substance 
by  reason  of  its  tendency  to  decompose  with  violence.  It 
contains  10  per  cent,  of  oxygen,  and  is  much  used  for 
washing  and  bleaching  textile  fabrics  and  as  a  general 
oxidizing  agent. 

Sodium  Acetate  (NaC2H3O2,3H2O)  is  a  colourless,  cry- 
stalline, efflorescent  body  soluble  in  water,  and  has  many 
commercial  applications. 

Sodium  Arsenates  are  salts  of  which  the  following  are 
well  known — viz.,  tri-sodium  ortho-arsenate  (or  arseniate), 
Na3AsO4,H2O  ;  di-sodium  hydrogen  ortho-arsenate,  Na2H, 
AsO4,i2H2O  ;  sodium  di-hydrogen  ortho-arsenate,  NaH2, 
AsSO4,H2O  ;  sodium  pyro-arsenate,  Na4As2O7 ;  and  sodium 
meta-arsenate,  NaAsO3. 

Sodium  Chlorate  (NaClO3)  and  Perchlorate  (NaClO4)  are 
white  crystalline  salts,  soluble  in  water,  prepared  much  in 
the  same  way  as  the  more  important  potassium  compounds 
and  used  for  the  same  purposes. 

Sodium  Bichromate  (Na2Cr2O7),  a  yellow,  crystalline, 
soluble  salt,  used  in  the  tanning  and  other  industries,  is 
prepared  in  a  corresponding  way  to  that  by  which  the 
more  important  potassium  bichromate  is  made. 


SODIUM— SOILS  449 

SODIUM  (Continued) — 

Sodium  Aluminate  (Na8Al2O4)  is  a  white  compound 
soluble  in  water,  and  used  as  a  mordant. 

Sodium  Hypochlorite  (NaCIO) — See  Chlorine,  p.  in. 

Sodium  Amalgam  (a  white  crystalline  substance),  ob- 
tained by  dissolving  sodium  in  from  2  to  10  per  cent,  of 
mercury  at  200°  C.,  is  often  used  as  a  reducing  agent. 

Sodium  Benzoate  (NaC7H5Oa)  is  a  crystalline  salt  soluble 
in  water,  used  as  a  food  preservative,  and  in  medicine. 

Sodium  Citrate  (2Na3,C6H5O7,iiH2O)  is  a  white  crys- 
talline salt,  soluble  in  water,  used  in  medicine  and  for 
compounding  non-alcoholic  drinks. 

Sodium  Cyanide — See  Cyanogen. 

Sodium  Formate  (NaCHO2)  can  be  prepared  in  a  crystal- 
line anhydrous  state  and  also  in  association  with  water 
(NaCHO2,H2O).  Both  are  soluble  in  water. 

Sodium  Ethoxide  (NaC2H5O)— Produced  by  the  action 
of  metallic  sodium  on  absolute  alcohol. 

Sodium  Ferricyanide  and  Ferrocyanide  resemble  the 
corresponding  potassium  salts,  and  are  used  industrially  for 
the  same  applications.  (See  Potassium,  p.  393.) 

Sodium  Glycerophosphate  (Na2C3H7PO6H2O)— A  yellow 
viscid  liquid,  soluble  in  water  and  alcohol ;  used  in  medicine. 

Sodium  Phenate  (or  Carbolate)  is  a  white,  deliquescent, 
crystalline  salt,  soluble  in  water  and  alcohol,  used  as  an 
antiseptic,  etc. 

Sodium  Silicate  (Soluble,  or  Water-Glass)  is  made  by 
calcining  quartz  with  caustic  soda  or  sodium  carbonate  and 
powdered  coal,  and  subsequent  extraction  with  water.  It 
is  known  in  the  anhydrous  form  (Na2SiO3),  and  also  as 
Na2SiO3,9H2O.  It  is  soluble  in  water,  and  used  in  fire- 
proofing  fabrics,  making-up  of  paints,  distempers,  cements, 
etc.,  also  for  preserving  eggs  and  many  other  applications. 

The  silicate  prepared  as  above  described  is  probably  an 
indefinite  mixture  and,  according  to  some  statements, 
silicon  dioxide  fused  with  sodium  carbonate  gives  the 
soluble  silicate  Na4SiO4. 

Sodium  Stannate — See  Tin. 

SOILS — The  outer  crust  of  the  earth,  consisting  mainly  of 
various  mineral  matters  resulting  from  the  action  of  air 
and  water  upon  rocks,  mixed  with  organic  (humous) 
substances  derived  from  the  decay  of  vegetable  growths 

29 


450  SOILS— SOLDER 

SOILS  (Continued) — 

and  animal  matter.  The  chemical  constitution  of  soils 
(from  which  plants  obtain  their  mineral  food)  varies 
according  to  the  nature  of  the  rocks  from  which  they  have 
resulted  by  weathering  and  they  are  roughly  described  as  of 
sand,  chalk,  clay,  or  loam,  etc.,  according  to  the  prevailing 
features.  It  has  been  suggested  that  the  soil  possesses  some 
of  the  attributes  of  colloids,  such  as  powers  of  absorption 
and  retention  of  water,  and  the  soil  moisture  is  certainly  of 
great  importance  inasmuch  as  it  constitutes  the  nutrient 
solution  for  growing  vegetation.  The  plant  residual  pro- 
ducts present  in  soil,  furnish  the  micro-organisms  which 
abound  in  them  with  food,  and  of  these,  the  two  more 
important  ones  are  cellulose  and  proteins  which  give  rise 
respectively  to  humus  and  ammonia.  The  humus  exercises 
important  physical  effects  in  the  soil,  and  it  is  from  the 
ammonia  which  becomes  oxidized  to  form  nitrates,  that 
growing  crops  obtain  their  nitrogen  food.  One  of  these 
sporing  organisms  easily  decomposes  cellulose  in  contact 
with  the  air,  and  is  named  Spirochceta  cytophaga,  and  gives  a 
simple  nitrogen  compound  such  as  a  nitrate  or  ammonia ; 
it  produces  among  other  things  a  pigment  like  carotin. 

Other  bacteria  and  fungi  bring  about  the  decomposition 
of  protein. 

Two  other  soil  organisms  which  flourish  particularly  in 
soil  dressed  with  farmyard  manure  are  Ps.  ftuorescens  and 
Ps.  candatus. 

The  changes  effected  by  the  many  micro-organisms  found 
in  various  soils  are  too  varied  to  be  dealt  with  in  a  work  of 
this  character,  but  some  other  details  are  given  under  the 
headings  of  Vegetation  and  Nitrification.  (See  also  Plant 
Colouring  Matters.) 

SOLANINE  (C62H93NO18)— A  poisonous  constituent  of  potatoes 
contained  to  the  extent  of  from  0-02  to  o-i  part  per 
thousand,  but  present  in  the  young  shoots  up  to  50  parts 
per  thousand. 

SOLAR  AND  STELLAR  CHEMISTRY— By  means  of  the  spectro- 
scope, it  has  been  ascertained  that  sodium,  magnesium, 
calcium,  barium,  copper,  zinc,  chromium,  nickel,  iron, 
hydrogen,  etc.,  exist  in  the  sun,  and  that  many  of  the 
chemical  substances  known  as  constituents  of  the  earth's 
composition  go  to  the  making  of  the  stars.  From  a  similar 
study  of  the  nebulae,  the  conclusion  has  been  drawn  that 
they  are  masses  of  glowing  gases. 

SOLDER — See  Alloys,  Lead,  and  Tin. 


"  SOLD  IS  »— SOL  UTION  4  5 1 

"SOLDIS" — A  disinfectant  of  phenolic  and  cresylic  character, 
miscible  with  water. 

SOLS— See  Colloid. 

SOLUBILITIES — See  Chemical  Combinations. 

SOLUBLE1— Admitting  of  being  dissolved  or  passing  into 
solution ;  for  example,  both  sugar  and  salt  are  soluble  in 
or  dissolved  by  water.  (See  Solution.) 

SOLUBLE  GLASS — See  Sodium  Silicate  (p.  449)  and  Silicon. 
SOLUTE— See  Solution. 

SOLUTION— If  a  spoonful  of  salt  be  placed  in  a  cup  of  water 
and  stirred,  the  salt  will  gradually  disappear ;  in  other 
words,  the  salt  is  dissolved  by  the  water  and  constitutes  the 
solute,  whilst  the  water,  which  was  previously  tasteless,  is 
the  solvent,  becomes  saline  in  taste,  and  is  called  a  solution 
of  salt.  When  sugar  is  placed  in  a  cup  of  hot  water  or  tea 
or  coffee,  it  dissolves,  making  the  liquid  sweet  in  character, 
and  the  mixture  becomes  in  the  same  sense  a  solution  of 
sugar.  Many  other  liquids  have  this  power  of  dissolving 
solid  substances ;  for  instance,  solid  camphor  is  easily 
dissolved  by  spirits  of  wine  (alcohol),  and  rosin  can  be 
dissolved  in  turpentine. 

Many  liquids  have  the  power  of  absorbing  or  dissolving 
certain  gases;  hydrochloric  acid  gas,  ammonia,  and 
chlorine  are  all  soluble  in  water,  absorption  in  this  sense 
being  the  same  thing  as  solution  or  solubility.  Further, 
many  liquids,  such  as  some  of  the  oils  and  hydrocarbons, 
are  soluble  in  alcohol,  ether,  and  some  other  liquids,  and 
solution  in  this  sense  is  also  identical  with  that  of  a  solid 
substance  dissolved  in  a  liquid. 

Gases  also  have  the  property  of  holding  substances  in 
solution ;  air,  for  example,  will  take  up  a  given  quantity 
of  water  according  to  the  temperature,  and  the  mixture 
may  be  regarded  as  one  of  water  dissolved  in  air.  (See 
Air,  p.  9.) 

There  is  good  reason  for  believing  that  in  some  cases 
when  substances  are  dissolved  in  liquids,  real  chemical 
combination  takes  place,  as,  for  example,  when  sodium 
carbonate  is  dissolved  in  water;  for  if  this  solution  be 
concentrated  by  evaporation  to  a  sufficient  extent,  there  is 
produced  on  cooling,  a  mass  of  crystals  of  common  washing 
soda  in  which  the  sodium  carbonate  is  definitely  combined 
with  water  (Na2CO3,ioH2O).  There  are  certain  conditions 
under  which  some  solutions  will  solidify  as  a  whole,  and 


452  SOLUTION— SORREL  (WOOD) 

SOLUTION  (Continued)— 

such  solids  were  at  one  time  regarded  as  cryohydrates,  but 
this  term  is  now  restricted  to  solidified  mixtures  of  solute 
and  solvent  (water),  which  are  of  the  same  composition  as 
the  solution,  the  "  eutectic  "  point  on  a  graph  being  that 
where  the  curves  of  temperature  representing  the  separation 
intersect. 

As  a  general  rule,  the  solubility  of  a  solid  in  a  liquid 
increases  with  the  temperature,  and  when  a  solution  will 
not  dissolve  any  more  of  the  solid  substance  at  any  particu- 
lar temperature  it  is  said  to  be  saturated,. 

A  solution  is  said  to  be  dilute  in  character  when  it  con- 
tains but  little  of  its  particular  ingredient,  and  is  described 
as  strong  or  concentrated  when  the  proportion  of  dissolved 
substance  is  great  in  quantity. 

Many  solutions  which  are  not  already  saturated,  can  be 
strengthened  or  concentrated  by  evaporating  off  some  of 
the  solvent.  For  instance,  a  dilute  solution  of  sodium 
nitrate  (nitre)  in  water  may  be  concentrated  by  the  applica- 
tion of  heat  (which  causes  the  evaporation  or  passing  oft 
in  the  state  of  vapour  of  some  of  the  water),  to  such  a 
stage  that  when  cooled,  the  excess  of  the  salt  will  crystal- 
lize out  on  cooling.  Similarly,  a  thin  solution  of  rosin  in 
turpentine  can  be  concentrated  by  heating  (which  causes 
the  evaporation  or  volatilization  of  some  of  the  solvent 
turpentine)  down  to  a  thick,  sticky  mass. 

On  the  other  hand,  strong  solutions  can  be  weakened 
(diluted)  by  the  addition  of  more  solvent.  (See  Saturation.) 

SOLVENT — See  Solution,  p.  451. 

SOLVENT    NAPHTHA— See    Naphtha,    p.    327,   and    Coal, 

p.  122. 

SOMBRERITE — An  impure  mineral  calcium  phosphate  (Ca3 
(PO4)2)  found  in  Sombrero  and  other  islands  of  the 
Antilles. 

SORBIC  ACID  (C6H8O2)— Found  in  the  unripe  sorb  apple 
(Sorbus  ancaparia)  and  mountain-ash  berries. 

SOREL  CEMENT — A  strong  binding,  made  by  mixing  calcined 
magnesia  with  concentrated  solution  of  magnesium  chloride 
which  sets  to  a  hard  mass  of  the  composition  MgCl2, 
5MgO,#H2O  (the  value  of  x  being  about  17). 

SORGHO  (Sorghum  saccharatum) — A  sugar-producing  grass 
resembling  maize  in  appearance. 

SORREL  (WOOD)  (Oxalis  acetosella) — A  plant  which,  in  common 
with  other  oxalis  and  rumex,  contains  potassium  oxalate. 


SOXHLET  APPARATUS—SPECIFIC  CRA  VlTY  FLASK    453 

SOXHLET  APPARATUS  is  of  glass  and  used  for  the  extrac- 
tion of  soluble  parts  of  substances  by  the  action  of  volatile 
solvents,  such  as  fat  from  milk  (absorbed  in  filter  paper). 

SOYA-BEAN  OIL — Sp.  gr.,  0-936  to  0*970 ;  melting-point, 
22°  to  3i°C.;  refractive  index,  1-4760  to  i'477  ;  saponifi- 
cation  value,  192  to  200;  and  iodine  value,  137  to  141.  A 
Chinese  product  expressed  from  soya-beans  (Soja  hispida 
and  S.  japonica),  and  used  in  soap-making,  as  a  cattle  food, 
also  in  the  manufacture  of  margarine  and  as  a  substitute 
for  linseed  oil  in  varnish-making.  Manchuria  produced 
2,000,000  tons  in  1918. 

SPANISH  FLIES— See  Cantharides. 

SPARTEIN  SULPHATE— A  salt  of  spartein  (C15H26N2),  a 
liquid  alkaloid  extracted  from  the  tops  of  Spartium  scoparium 
(broom)  and  used  in  medicine. 

SPATHIC  IRON-ORE— A  mineral  ferrous  carbonate  (FeCO3). 

SPATULA — A  flat  blade  used  for  transferring  solid  or  pasty 
substances  from  one  container  to  another.  Spatulas  are 
made  of  various  materials,  according  to  the  nature  of  the 
substance  to  be  manipulated — some  of  steel  fixed  in  a 
wooden  handle;  others  of  ivory,  platinum,  nickel,  alu- 
minium, etc. 

SPEARMINT  OIL — An  essential  oil  containing  carvone  dis- 
tilled from  the  fresh  American  herb  Mentha  viridis  (ordinary 
garden  mint)  and  the  German  Mentha  crispa.  It  has  a 
sp.  gr.  of  0-92  to  0-94,  rotation  —36°  to  -48°,  and  is  used 
in  medicine,  for  flavouring,  and  in  confectionery. 

SPECIFIC  GRAVITIES— The  relative  weights  of  equal  volumes 
of  gases  compared  with  hydrogen  as  unit,  are  known  as 
their  specific  gravities  or  vapour  densities.  The  specific 
gravities  of  liquids  and  solids  are  their  relative  weights  as 
compared  with  the  density  of  water  as  the  unit.  (See 
Hydrometer  and  Vapour  Densities.) 

SPECIFIC  GRAVITY  FLASK— This  is  used  for  determining  the 
specific  gravity  of  fluids  by  weight,  and  in  practice  it  is 
usual  to  employ  a  stoppered  flask  filled  at  15 -5°  C.,  the 
stopper  being  inserted  so  that  the  liquid  overflows  and  no 
air  is  left  in  the  flask.  Its  weight  (after  drying  it  externally) 
as  compared  with  that  of  water  determines  the  specific 
gravity.  The  weight  of  the  liquid  (after  deducting  that  of 
the  empty  dry  flask)  having  been  ascertained,  and  that  of 
the  same  quantity  of  water  at  the  same  temperature  being 
known,  the  specific  gravity  of  the  liquid  is  ascertained  by 
dividing  it  by  the  latter.  (See  also  Hydrometer.) 


454 


SPECIFIC  HEATS 


SPECIFIC  HEATS— It  is  a  known  fact  that  equal  weights  of 
different  substances  absorb  different  quantities  of  heat 
through  the  same  range  of  temperature — water,  for  example 
(which  exhibits  the  highest  thermal  capacity  of  all  known 
substances),  requires  thirty  times  the  amount  required  by 
the  same  quantity  of  mercury  to  raise  it  through  a  given 
number  of  degrees.  These  relative  capacities  furnish  the 
so-called  specific  heats  of  substances,  which  may  be  defined 
as  the  ratios  of  their  thermal  capacities  to  that  of  an  equal 
weight  of  water  ;  thus,  the  specific  heat  of  water  being  taken 


Element. 

Specific 
Heat. 

Atomic 
Weight 
taken  as 

Atomic 
Heat. 

Antimony 

0-0495 

I2O"2 

5'95 

Arsenic 

0*083 

74-96 

6-22 

Bismuth 

0*0305 

208 

6-34 

Cobalt 

0*10303 

58-97 

6-08 

Copper 

0*09232 

63-57 

5*1 

Gold 

0-03035 

197-2 

5-99 

Iron 

0-10983 

55^4 

6-36 

Lead 
Lithium 

0-0315 
0-94 

207-2 
6-94 

6-52 
6-52 

Manganese   ... 

O-I2I 

54'93 

6-70 

Mercury 

0-0334 

200*6 

6-70 

Nickel 

0*10842 

58'68 

6-16 

Platinum 

0-03147 

195-2 

6*14 

Potassium 

0-166 

39*  I 

6-51 

Silver 

0-0559 

107-88 

6*03 

Sodium 

0-29 

23 

670 

Tin 

0*0559 

118-7 

6-65 

Zinc 

0-0939 

6"5'37 

6-14 

j 

as  the  unit,  that  of  mercury  is  ^th  or  0-033.  There  is  a 
definite  relation  between  the  specific  heats  and  the  atomic 
weights  of  various  solid  elements,  the  former  being  inversely 
proportional  to  the  numbers  known  as  their  atomic  weights. 
This  law,  known  as  that  of  Dulong  and  Petit,  is  expressed 
by  stating  that  the  thermal  capacities  of  atoms  of  the 
elements  in  the  solid  state  are  equal,  and  the  table  given 
above  briefly  illustrates  this  relationship.  The  molecular 
heat  of  a  compound  is  the  sum  of  the  atomic  heats  of  its 
constituent  elements. 


SPECTROSCOPE  455 

SPECTROSCOPE — An  instrument  by  means  of  which  the  light 
emitted  by  strongly  heated  substances  can  be  examined, 
as  described  herein.  It  is  constructed  of  one  or  more 
prisms  by  which  the  coloured  rays  are  separated  when  light 
is  made  to  pass  through  them.  This  analysis  or  splitting 
up  of  light  into  the  different  colours  of  which  it  is  constituted, 
furnishes  what  is  termed  the  prismatic  spectrum ;  each 
colour  having  its  own  peculiar  refrangibility  ranging  from 
the  red  rays  which  are  the  least  refrangible,  to  the  deep 
violet  which  are  most  refrangible,  at  the  other  end  of  the 
rainbow. 

Various  chemical  salts  when  heated  in  the  blow-pipe  or 
nearly  colourless  Bunsen-burner  flame,  impart  a  peculiar 
colour  which  is  indicative  of  their  nature,  but  where 
mixtures  are  concerned,  the  indication  is  lost  on  account 
of  the  merging  or  blending  of  the  various  colours  which 
takes  place.  Sodium  compounds  give  a  yellow  colour  to 
flame;  potassium  salts  tinge  the  flame  purple;  whilst 
lithium  salts  communicate  a  crimson-red  colour.  The 
colour  given  by  the  salts  of  rubidium  and  caesium  is  in- 
distinguishable by  the  naked  eye  from  that  of  potassium 
compounds,  but  when  these  coloured  flames  are  examined 
through  the  telescope  (forming  a  part  of  the  instru- 
ment under  description)  the  spectrum  affords  an  easy  and 
assured  method  of  diagnosis,  inasmuch  as  the  chemical 
salts  under  examination  furnish  their  distinct  bright  bands 
of  light.  Sodium  compounds  give  a  distinct  line  or  group 
of  lines  in  the  yellow,  lithium  gives  one  band  in  the  red  and 
another  in  the  yellow,  and  potassium  also  gives  two  bands, 
one  in  the  deep  red  and  another  in  the  violet,  and  when 
mixtures  are  examined,  the  individual  or  distinctive  bands 
are  all  respectively  revealed. 

This  method  of  detection  is  so  delicate  that  so  small  a 
part  as  T8Qooooooth  of  a  grain  of  sodium  salt  and  ^oio00th 
of  a  grain  of  lithium  can  be  detected. 

Characteristic  spectra  are  afforded  not  only  by  sub- 
stances which  give  colour  to  flame  but  by  every  elementary 
body  when  heated  to  the  degree  at  which  its  vapour 
becomes  luminous. 

Many  of  the  elements  were  discovered  by  the  use  of 
spectrum  analysis,  including  caesium,  rubidium,  thallium, 
indium,  helium,  and  gallium,  and  before  anything  was 
known  of  their  unique  chemical  properties. 

The  instrument  consists  in  its  simplest  form  of  a 
prism  (A)  fixed  upon  a  stand  placed  in  line  with  a  hollow 
tube  (B)  provided  with  a  slit  or  shutter  (C)  at  the  end 


456  SPECTROSCOPE 

SPECTROSCOPE  (Continued)— 

opposite  to  which  the  flame  is  placed  for  examination. 
The  rays  of  light  passing  along  this  tube  through  the  slit 

are  received  upon 
the  prism  through 
D    a  lens  fixed  in  the 
tube     called      the 
collimator      which 
renders    the    rays 
parallel,    and     the 
refracted  rays   are 
received     by     the 
observer  using  the 
telescope   (D)  (see 
Figure),    which    is 
placed  in  such  posi- 
tion that  the  bent  rays  fall  upon  its  lens,  and  are  magnified 
by  it.      The   illustration   is   that  of    one   of   Browning's 
spectroscopes. 

Emission  spectra  can  be  produced  in  a  number  of  ways — 
viz.,  by  the  use  of  flame  such  as  that  of  a  Bunsen  lamp  in 
respect  of  the  more  or  less  volatile  metallic  salts  ;  or  by  the 
electric  arc,  which  furnishes  a  much  higher  temperature, 
the  spectrum  being  obtained  by  placing  the  substance  to 
be  examined  into  the  arc  between  the  carbon  poles ;  or  by 
means  of  the  sparks  from  an  induction  coil  made  to  pass 
between  small  poles  of  the  substance,  or  discharged  through 

fases— a  method  which  can  also  be  applied  to  solutions ;  or, 
nally,  by  the  use  of  cathode  streams  for  the  production  of 
phosphorescence  in  solid  substances. 

'  The  relation  between  the  powers  of  emission  and  those 
of  absorption  for  rays  of  the  same  wave-lengths  is  constant 
for  all  bodies  at  the  same  temperature. 

Organic  solutions  were  first  examined  by  photographing 
the  spark  spectrum  of  an  alloy  of  tin,  lead,  cadmium,  and 
bismuth,  as  obtained  through  a  solution  of  the  subject 
under  examination. 

The  bright  yellow  sodium  lines  are  made  to  appear  as 
dark  lines  or  spaces,  by  allowing  the  rays  of  a  white  light 
like  that  of  the  oxyhydrogen  flame  or  an  incandescent 
platinum  wire  to  pass  through  a  flame  coloured  by  a 
sodium  compound,  and  then  to  fall  upon  the  slit  of  a 
spectroscope,  because  the  yellow  flame  absorbs  the  same 
kind  of  light  as  it  emits,  and  so  each  substance  in  the 
vaporous  state  has  the  power  of  absorbing  the  same  rays 
as  it  emits,  or  being  opaque  to  same.  This  accounts  for 


SPECTROSCOPE— SPIRITS  OF  WINE  457 

SPECTROSCOPE  (Continued)— 

the  dark  spaces  or  so-called  Fraunhofer  lines  observed  in 
the  solar  atmosphere,  these  being,  as  is  believed,  bright 
lines  reversed,  and  indicative,  therefore,  of  the  presence  in 
the  sun's  atmosphere  of  those  substances  which  are  capable 
of  yielding  the  coincident  bright  lines,  including  iron, 
sodium,  calcium,  magnesium,  chromium,  barium,  copper, 
zinc,  hydrogen,  and  nickel. 

By  the  investigation  of  emission  and  absorption  spectra, 
using  a  variety  of  appliances  adapted  to  the  many  different 
substances  requiring  examination,  it  has  been  found  possible 
not  only  to  acquire  a  very  definite  knowledge  of  the  constitu- 
tion of  the  sun's  atmosphere,  the  fixed  stars,  and  the  so-called 
nebulas,  but  these  methods  have  been  turned  to  account 
for  the  identification  of  precious  stones,  dyes,  and  colouring 
matters;  the  detection  of  alum  in  wines  and  fruit  juices, 
blighted  wheat  in  flour,  and  bloodstains ;  the  estimation  of 
alkaloids,  the  valuation  of  indigo  samples,  the  examination 
of  essential  oils,  sugar  analysis,  etc.  The  spectroscope  has 
also  proved  of  great  value  in  the  investigation  of  many 
organic  compounds,  radical  groups  such  as  CH2,  CH3, 
NH2,  C6H6,  HO,  etc.,  all  giving  characteristic  absorption 
bands. 

SPECTRUM — The  band  of  colours  into  which  white  light  can 
be  broken  up,  as,  for  example,  when  passed  through  a 
prism.  (See  Light  and  Spectroscope.) 

SPECULAR  IRON-ORE— Ferric  oxide  (Fe2O3). 
SPEISS-COBALT— See  Cobalt. 
SPELTER — A  commercial  name  for  zinc. 
SPERM  OIL— See  Fish  Oils. 
SPERMACETI— See  Waxes. 

SPERRYLITE — A  very  rare  mineral  containing  platinum  com- 
bined with  arsenic  (PtAs2). 

SPHAGNUM — A  club  moss  (Sph.  acutifolium)  which  grows 
abundantly  on  peat  moors,  and  which  has  proved  of  great 
utility  as  a  soft,  absorbent,  surgical  dressing  mildly  anti- 
septic in  character. 

SPIKE  OIL— See  Lavender  (Spike)  Oil. 

SPINELLE — A  natural  crystalline  magnesium  aluminate 
(MgO,Al2O3),  used  as  a  gem  and  as  an  abrasive. 

SPIRITS  OF  WINE— Alcohol  of  indefinite  strength.  (See 
Alcohol.) 


458  SPODUMENE-STARCH 

SPODUMENE— See  Lithium. 

"  SPONDITE  "—A  substitute  for  glass,  being  an  application  of 
cellulose  acetate  dope  to  wire  netting. 

SPONGES  are  living  organisms  of  various  species  (found 
adherent  to  rocks  in  the  Mediterranean  and  elsewhere), 
the  tissues  of  which,  constitutionally,  are,  from  a  chemical 
point  of  view,  nearly  related  to  the  fibroin  of  silk. 

SPONGY  PLATINUM^See  Platinum  and  Catalytic. 

SPONTANEOUS  COMBUSTION  ensues  as  a  result  of  the  develop- 
ment of  heat  arising  from  chemical  changes ;  thus,  cotton 
waste  soaked  in  linseed  oil  will  sometimes  fire  in  consequence 
of  the  rapid  oxidation  of  the  oil.  Similarly  phosphorus  ex- 
posed to  the  air  will  take  fire,  and  burnt  lime  during  slaking 
with  water  develops  enough  heat  to  fire  wood  that  may 
happen  to  be  in  contiguity. 

SPBUCE  OIL— Distilled  from  the  leaves  and  twigs  of  Picea 
alba  and  P.  nigra,  containing  pinene,  cadinene,  and  bornyl 
acetate.  It  is  colourless,  of  pleasant  odour,  with  sp.  gr. 
about  0-9,  optical  rotation  -22°  to  -25°;  soluble  in  al- 
cohol and  ether,  and  used  in  medicine  and  perfumery. 

STALACTITES — Deposits  of  calcium  carbonate  like  icicles, 
formed  from  dripping  water  in  the  roofs  of  calcareous 
caves,  due  to  the  escape  of  carbon  dioxide  from  a  solution 
of  calcium  carbonate  dissolved  in  water  and  previously 
held  in  solution  by  its  agency. 

STALAGMITES — Similar  deposits  growing  upon  the  floor  of 
caves  out  of  the  water  dropped  from  above. 

STANDARD  SOLUTIONS — See  Normal  Standard  Solutions  and 
Reagents. 

STANNATES— See  Tin. 

STAR-ANISE  OIL — A  colourless,  volatile  oil  from  the  seeds  of 
Ilicium  anisatum  (China  and  Japan)  containing  anethol  and 
used  for  flavouring,  etc. 

STARCH  (Amylum)  is  found  present  in  some  of  the  parts  of 
nearly  all  plants,  in  the  form  of  organized  or  structural 
granules  of  varying  size,  and  abundantly  in  wheat,  maize, 
barley,  oats,  arrowroot,  rice,  and  the  potato.  Chemically 
it  is  a  carbohydrate  (CSH10O6), — this  formula  representing 
the  proportions  of  the  constituent  elements,  the  number  in 
the  molecule  being  unknown. 

Potatoes  contain  on  an  average,  about  20  to  27  per  cent, 
of  starch  ;  wheat  from  50  to  75  per  cent. 

Sago  is  a  starch  produced  from  the  sago- palm ;  tapioca 
is    made    from    the    Jatropha   manihot ;   arrowroot   is    the 


STARCH— STEARIC  ACID  459 

STARCH  (Continued)— 

starch  of  the  tropical  plant  Mavanta  arundinacea  ;  and  arum 
is  a  starch  similar  to  sago  obtained  from  the  root  of  A  yum 
maculatum. 

Lichenin — otherwise  known  as  moss  starch — is  contained 
in  many  lichens,  including  Iceland  moss ;  inulin  is  another 
variety,  present  in  dahlia  and  other  roots ;  whilst  glycogen 
is  a  form  of  animal  starch  found  in  the  livers  of  mammalia. 

In  plant  life,  starch  is  converted  into  sugar  during  the 
transference  of  the  sap. 

Starch  is  not  soluble  in  cold  water,  but  when  heated  with 
water  it  swells  up  and  assumes  a  more  or  less  pasty  con- 
dition, forming  a  kind  of  emulsion,  commonly  known  in 
chemical  laboratories  as  "starch  solution,"  although  but 
little  passes  into  real  solution. 

Both  in  its  soluble  and  insoluble  conditions  starch  com- 
bines with  iodine,  forming  a  deep  blue  compound. 

If  starch  be  heated  in  the  dry  state  for  some  hours  at  a 
temperature  of  200°  C.,  its  character  becomes  changed,  and 
the  product  is  quite  soluble  in  water,  being  what  is  known 
commercially  as  dextrine  or  British  gum,  as  used  by  calico- 
printers  for  mixing  with  their  colours,  also  as  an  adhesive, 
for  sizing,  and  other  purposes.  By  the  action  of  dilute 
acids  and  ferments,  starch  yields  a  number  of  sugar-like 
bodies  known  as  dextrose,  maltose,  etc.,  which  are  largely 
employed  in  brewing  and  other  industries,  being  substances 
which,  like  ordinary  sugar,  admit  of  being  fermented  into  al- 
cohol. (See  Carbohydrates. )  By  a  special  process  of  fermen- 
tation, acetone  is  now  commercially  prepared  from  starch. 

Starch  is  used  in  laundries  and  the  finishing  of  textiles  ; 
also  in  the  manufacture  of  adhesives,  invalids'  foods, 
dextrine,  and  as  a  face-powder,  etc. 

STASSFURT  SALTS — The  dried-up  residue  of  a  great  pre- 
historic ocean,  consisting  largely  of  potassium  salts.  (See 
Potassium.) 

STEARIC  ACID  (C18H36O2)  (sp.  gr.  0-8428)— A  solid  fatty  acid 
found  present  in  most  animal  and  vegetable  fats  and  oils, 
and  generally  associated  in  varying  proportions  with  palmitic 
and  oleic  acids  ;  all  in  combination  with  glycerine  in  the 
form  of  glycerides  or  glyceryl  esters.  It  is  most  abundant 
in  the  more  sojid  fats  and  forms  hard  soap  when  saponified, 
setting  free  the  glycerine  as  explained  elsewhere.  (See 
Soaps.)  It  can  be  readily  prepared  from  beef  or  mutton 
fat  and  when  pure  is  white,  crystalline,  and  melts  at  68°  C. 
It  is  largely  used  in  making  candles.  (See  Fats.) 


460  STEA  R1N— STRONTIUM 

STEARIN  ((C18H35O2)3C3H5)— The  glyceride  or  glyceryl  ester 
of  stearic  acid,  occurring  as  a  solid  constituent  of  fats  and 
yielding  potassium  stearate  (soap)  and  glycerine  (glycerol) 
upon  saponification  with  alcoholic  potash.  It  melts  at 
71°  C.,  has  a  sp.  gr.  0-862,  and  is  soluble  in  ether,  chloro- 
form, and  carbon  disulphide.  (See  Fats.) 

STEATITE— A  form  of  talc,  slabs  of  which  are  often  used  for 
making  firestones  in  furnaces  and  stoves. 

STEEL — See  Iron,  p.  270. 

STELLITE — A  hard  alloy  of  cobalt,  chromium,  and  tungsten 
melted  together  in  an  electric  furnace  at  over  1,500°  C. 
used  for  high-speed  cutting  tools,  for  making  cutlery  and 
surgical  implements,  and  for  use  as  a  nitric  acid  resistant 
material. 

STEPHANITE  (5AgS.Sb2S3)— A  native  sulphantimonite  of 
silver. 

STEREO-ISOMERISM— See  Isomerism. 
STIBILITE— Native  oxide  of  antimony. 

STIBNITE    (Grey  Antimony)— Native   sulphide  of    antimony 

(Sb2S3). 
STICK  LAC— Shellac. 

STILBITE — A  mineral,  crystalline  hydrated  silicate  of  calcium 
and  aluminium. 

STILL— See  Retort. 

STOCKHOLM  TAR— A  tar  distilled  from  the  resinous  wood  ot 
the  pine,  and  largely  used  in  connection  with  wooden 
shipbuilding  for  caulking.  It  is  soluble  in  turpentine. 

STORAX  (Styrax) — See  Balsams  and  Styrene. 

STROMEYERITE — A  mineral  double  sulphide  of  silver  and 
copper  (Ag2S,Cu2S)  found  in  Arizona  and  elsewhere. 

STRONTIANITE — Native  carbonate  of  strontium  (SrCO3). 

STRONTIUM  (Sr)— Atomic  weight,  87-6;  sp.  gr.,  2-54;  melt- 
ing-point, 900°  C.  Strontium  is  contained  in  the  mineral 
known  as  strontianite  in  the  form  of  carbonate  (SrCO3j,  in 
brewsterite  as  silicate,  and  in  celestine  as  sulphate  (SrSO4). 

The  metal  is  soft  and  of  a  pale  yellow  colour,  and  has 
to  be  kept  in  naphtha,  as  it  readily  oxidizes  in  the  air  and 
possesses  the  property  of  decomposing  water.  It  is  pre- 
pared by  the  electrolysis  of  the  fused  chloride.  Like 
magnesium,  it  burns  brilliantly  upon  ignition  in  the  air, 
producing  the  monoxide  SrO. 


STRONTIUM— STY  RONE  461 

STRONTIUM  (Continued) — 

Strontium  Monoxide  (strontia),  like  lime,  combines  with 
water,  with  evolution  of  heat,  forming  the  hydroxide 
(Sr(HO)2)  which  is  strongly  alkaline  and  more  soluble  in 
water  than  calcium  hydroxide.  It  is  used  on  a  large  scale 
in  the  purification  of  sugar,  with  which  it  forms  a  combina- 
tion (saccharate  of  strontia)  which  can  be  decomposed  by 
carbon  dioxide.  (See  Saccharate,  Strontium  and  Sugar.) 

There  is  a  dioxide  (SrO2)  which  upon  heating  to  redness, 
parts  with  oxygen  and  is  reduced  to  the  monoxide.  It 
is  obtained  in  pearly  crystals  having  the  composition 
SrO2,8H2O  by  adding  hydrogen  peroxide  to  a  solution  of 
the  hydroxide,  and  is  used  to  some  extent  in  bleaching. 

Strontium  Chloride  (SrCl26H2O)  is  a  white,  crystalline 
salt,  soluble  in  water  and  alcohol  and  used  in  the  pro- 
duction of  red  flames. 

Strontium  Nitrate  (Sr(NO3)2),  obtained  by  dissolving  the 
oxide  or  carbonate  in  dilute  nitric  acid,  is  a  white  crystalline 
salt  extensively  used  in  the  production  of  red  fireworks. 
It  crystallizes  with  water  as  Sr(NO?)24H2O,  and  when 
heated  with  combustible  matter,  the  mixture  takes  fire  and 
burns  with  a  characteristic  crimson  colour. 

Strontium  Carbonate  is  a  white  substance,  practically  in- 
soluble in  water,  used  in  pyrotechnics  and  the  manufacture 
of  iridescent  glass. 

Strontium  Sulphate  (SrSO4)  is  white  and  practically 
insoluble  in  water. 

Strontium  Saccharate — See  Saccharate,  Strontium. 

STRYCHNINE  (C21H22N2O2) — An  exceedingly  poisonous  white, 
crystalline  alkaloidal  base  extracted  from  Strychnos  nux 
vomica  and  St.  Ignatius'  beans,  etc.  It  melts  at  268°  C., 
is  soluble  in  chloroform  and  used  in  medicine. 

STUCCO — A  coloured  form  of  plaster  of  Paris  prepared  with  a 
solution  of  size. 

STYRENE  (Styrol)  (C6H5CH.CH2)— A  refractive,  oily,  yellow- 
ish liquid  of  aromatic  odour,  with  a  sp.  gr.  of  0-912  and 
boiling-point  146°  C. ;  soluble  in  alcohol  and  ether,  obtained 
from  liquid  storax  (sty rax),  and  used  in  medicine.  It 
polymerizes  spontaneously  upon  standing,  into  a  jelly-like 
mass.  (See  also  Cinnamic  Alcohol.) 

STYRONE— See  Cinnamic  alcohol. 


462  SUBERIC  ACID— SUGAR 

SUBERIC  ACID  (C8H14O4) — A  member  of  the  oxalic  series  of 
acids,  originally  obtained  by  the  action  of  nitric  acid  upon 
cork,  but  easily  prepared,  similarly,  from  oleic  acid  or  other 
fatty  acids.  It  is  a  crystalline  body  which  melts  at  140°  C., 
dissolves  readily  in  boiling  water,  and  mixes  with  fixed  oils. 
When  strongly  heated,  it  gives  off  suffocating  vapours. 

SUBLIMATE — A  solid  deposit  resulting  from  the  condensation 
of  a  vapour. 

SUBLIMATION — A  sort  of  dry  distillation  or  volatilization  of 
solid  substances  like  camphor,  iodine,  naphthalene,  and 
sulphur,  and  the  condensation  of  their  vapours  anew  into 
solid  form. 

SUBSTITUTION  PRODUCTS  are  those  which  result  from  the 
substitution  of  one  element  or  radical  by  another  in  any 
chemical  substance.  For  example,  methane  (CH4)  yields 
four  substitution  products  with  chlorine,  by  replacement  of 
respectively  i,  2,  3,  and  4  atoms  of  hydrogen,  represented 
by  CH3C1,  CH2C12,  CHC13,  and  CC14.  Again,  nitro- 
benzene (C6H5NO2)  is  a  substitution  product  obtained 
from  benzene  (C6H6)  by  the  replacement  of  i  atom  of 
hydrogen  by  the  group  NO2. 

SUBSTRATE— See  Enzymes,  p.  178. 

SUCCINAMIDE  (C4H8N2O2)— The  amide  derivative  of -succinic 
acid,  produced  by  the  interaction  of  ammonia  and  ethyl 
succinate. 

SUCCINIC  ACID  (C4H6O4)  is  found  amongst  the  products  of 
the  distillation  of  amber  and  in  certain  animal  juices  and 
resins.  It  can  be  prepared  in  several  ways,  including  the 
oxidation  of  butyric  acid  and  the  hydrolysis  of  ethylene 
dicyanide.  It  forms  large  colourless  crystals,  is  soluble 
in  water,  fuses  at  186°  C.,  and  boils  at  235°  C.,  when  its 
vapour  is  dissociated  into  succinic  anhydride  (C4H4O3)  and 
water.  Its  alkaline  salts  are  soluble  in  water. 

SUCCINIMIDE  (C4H5NO2) — The  imide  derivative  of  succinic 
acid ;  a  crystalline  substance  produced  by  heating  hydrogen- 
ammonium  succinate. 
SUCRASE — Invertase. 

SUCROSE— Cane  Sugar. 

SUET — See  Fats. 

SUGAR  (Cane  Sugar,  Beet  Sugar,  Saccharose,  Sucrose) 
(C^H^OyJ — A  hard,  white,  crystalline,  sweet  substance, 
occurring  in  the  stems  or  juices  of  certain  grasses  and  many 
plants,  including  the  red-beet  and  sugar-maple,  and  par- 
ticularly in  the  sugar-cane,  from  which  it  is  produced  by 


SUGAR— SUGAR  OF  MILK  463 

SUGAR  (Continued)— 

pressure  between  rollers  and  subsequent  purification.  The 
sugar  juice,  as  expressed  from  the  canes,  is  first  of  all 
defecated — that  is,  treated  with  milk  of  lime  to  neutralize 
acidic  ingredients,  and  boiled  to  coagulate  the  albuminous 
matters  contained  in  the  juice,  after  which  the  excess  of 
lime  is  carbonated  by  the  passage  of  carbon  dioxide.  The 
settled  or  filtered  liquor  resulting  from  this  preliminary 
treatment  is  evaporated  in  vacuo,  and  yields  upon  cooling 
a  mixture  of  sugar  crystals  and  syrup,  the  former  being 
separated  from  the  treacle  by  centrifugalization.  It  is 
refined  by  dissolving  in  water  and  decolourization  by  perco- 
lation through  a  filter  of  animal  charcoal,  after  which  it  is 
again  concentrated  and  crystallized.  The  molasses  or 
treacle  containing  some  crystalline  sugar  still  in  solution 
is  treated  with  a  solution  of  strontium  hydroxide,  which 
forms  an  insoluble  combination  with  it,  and  after  removal 
by  filtration,  is  decomposed  by  the  action  of  carbon  dioxide 
upon  it  as  suspended  in  water,  thus  forming  insoluble 
strontium  carbonate,  the  sugar  meanwhile  passing  into 
solution,  from  which  it  is  recovered  by  concentration  and 
crystallization.  The  molasses  finally  left  is  used  for  making 
rum,  or  ordinary  alcohol,  and  the  "begasse,"  or  crushed 
sugar-cane  mass  is  used  as  fuel. 

In  course  of  the  evaporation  of  maple  sap  to  the  syrup 
stage,  a  precipitate  called  "  sand,"  and  containing  from 
60  to  80  per  cent,  of  calcium  malate,  is  deposited,  and  finds 
use  in  the  preparation  of  baking-powders,  etc. 

Sugar  is  also  manufactured  from  beetroots,  and  is 
marketed  in  many  forms,  such  as  loaf,  cube,  lump,  granular, 
icing,  etc.  The  so-called  soft  sugars  contain  a  proportion 
of  molasses,  also  of  invert  sugar. 

Sugar  melts  at  160°  C.,  into  what  is  known  as  barley- 
sugar,  and  when  further  heated  forms  "caramel."  Sub- 
jected to  the  action  of  acids,  cane  sugar  is  "  inverted  "  by 
hydrolysis,  and  whereas  it  was  originally  dextro-rotatory, 
the  invert  sugar  which  is  formed  is  laevo-rotatory  and 
consists  of  a  mixture  of  fructose  and  glucose,  (See  also 
Carbohydrates,  Saccharoses,  and  Glucose.) 

Sugar  in  its  several  forms  is  a  valuable  food,  and  is 
largely  used  as  a  sweetener,  in  the  preparation  of  syrups, 
preserves,  and  jams,  and  for  the  manufacture  of  alcohol,  etc. 

SUGAR-CANE   WAX— See  Waxes. 
SUGAR  OF  LEAD— See  Lead. 
SUGAR  OF  MILK— See  Lactose. 


464  SUINT-SULPHUR 

SUINT — A  peculiar  fatty  body  found  present  in  sheep's  wool, 
containing  also  a  quantity  of  potash.  A  fleece  weighing 
9  pounds  contains  about  20  ounces  of  suint,  of  which 
about  one-third  is  potash.  The  fat  is  used  for  soap  making 
and  in  the  preparation  of  lanoline.  (See  also  Degras  and 
Wool- wax.) 

SULPHATES-See  Sulphur. 

SULPHIDES — See  Chemical  Compounds  and  Sulphur  Com- 
pounds. 

SULPHIDES  (Organic) — The  substances  known  as  mercaptans 
are  in  the  nature  of  sulphides ;  ordinary  mercaptan  is  ethyl 
hydrosulphide  (C2H5HS)  and  ethyl  sulphide  is  (C2H5)2S. 
(See  Mercaptans.) 

SULPHITES— See  Sulphur. 

SULPHOCARBOLATES  are  compounds  prepared  from  phenol- 
sulphonic  acid  (C6H5SO3H).  The  zinc  salt  is  used 
medicinally. 

SULPHOCYANIC  ACID,  otherwise  known  as  thiocyanic  acid 
(CNSH),  is  the  sulphur  analogue  of  cyanic  acid  (CNOH). 

SULPHOC YANIDES  (Sulphocyanates)  are  combinations  of  bases 
with  sulphocyanic  acid.  By  fusion  of  sulphur  with  potas- 
sium cyanide  or  sodium  cyanide  the  corresponding  potas- 
sium sulphocyanide  (KCNS)  and  sodium  sulphocyanide 
(NaCNS)  are  formed.  They  are  readily  soluble  in  water 
and  are  not  poisonous. 

Sulphocyanides  can  be  prepared  from  the  ammoniacal 
liquor  of  gasworks. 

SULPHONAL  (Sulphone  Methane)  (C7H16S2O4  or  (CH3)2: 
C(SO2.C2H5)2) — A  colourless  crystalline  substance,  used 
as  a  soporific  and  hypnotic.  It  melts  at  125°  C.  and  is 
soluble  in  alcohol. 

SULPHONATION — The  treatment  of  organic  bodies  with  sul- 
phuric acid  whereby  sulphonic  acids  are  produced,  the 
products  containing  the  group  SO2,OH.  Thus  benzene 
(C6H6),  treated  with  fuming  sulphuric  acid,  yields  benzene 
sulphonic  acid  (C6H5,SO2,OH) : 

C6H6  +  H2S04  =  C6H6SO3  +  H2O. 

SULPHUR  (S) — Atomic  weight,  32.  Large  quantities  of  sulphur 
are  found  naturally  in  Japan,  Spain,  and  the  United  States 
of  America,  also  in  volcanic  districts,  including  Italy,  Sicily, 
and  Iceland,  and  there  are  considerable  beds  of  it  in  the 
Locken  mines  south-east  of  Trondhjem  (in  Scandinavia), 


SULPHUR  465 

SULPHUR  (Continued)— 

Transylvania,  China,  India,  and  California.  The  Sicilian 
production  of  sulphur  in  1919  was  181,374  tons.  Sulphur 
is  also  found  naturally  in  various  forms  as  sulphides,  of 
which  the  best  known  are  galena,  or  lead  sulphide  (PbS), 
zinc  blende,  or  zinc  sulphide  (ZnS),  iron  pyrites,  or  iron 
sulphide  (FeS2),  and  copper  pyrites  (Cu2Fe2S4).  (See  Pyrites.) 

Cinnabar  is  a  natural  mercury  sulphide  (HgS).  The 
mineral  gypsum,  or  calcium  sulphate,  contains  sulphur 
in  combination  with  calcium  and  oxygen  and  water 
(CaSO4.2H2O) ;  whilst  heavy  spar  also  contains  sulphur  in 
the  form  of  barium  sulphate  (BaSO4). 

Sulphur  is  obtained  from  its  crude  natural  form  by 
melting  and  vaporization,  by  which  means  it  is  sublimed 
and  thus  purified.  As  a  constituent  of  pyrites,  it  is  utilized 
in  the  manufacture  of  sulphuric  acid  described  elsewhere 
(p.  468),  and  it  can  be  made  from  the  sulphurized  oxide  of 
iron  resulting  from  the  process  used  in  gasworks  for  free- 
ing the  gas  from  hydrogen  sulphide.  This  is  done  either  by 
burning  off  the  sulphur  into  the  form  of  sulphur  dioxide 
or  oxidation  of  the  sulphurized  mass,  thereby  revivifying 
the  ferric  oxide  : 

2FeS  +  3O  +  3H20  =  2Fe(OH)3  +  28, 

the  sulphur  thus  set  free  being  subsequently  distilled  or 
burnt  off. 

The  total  amount  of  sulphur  obtained  in  a  pure  state 
annually,  is  about  800,000  tons,  and  about  one  half  of  this 
comes  from  Sicily  and  the  U.S.A. 

A  German  war-time  process  for  preparing  sulphur  was 
based  upon  the  reaction  that  takes  place  between  calcium 
sulphide  and  magnesium  chloride  when  boiled  together, 
the  hydrogen  sulphide  (H2S)  thus  liberated  being  burned 
in  the  air  under  such  conditions  that  only  the  hydrogen 
is  burned  and  the  sulphur  is  deposited. 

When  H2S  and  SO2  are  mixed  together,  all  the  sulphur 
is  deposited  according  to  the  equation — 

H2S  +  SO2  =  2H2O  +  28. 

The  calcium  sulphide  primarily  employed  and  converted 
into  sulphate  is  reconverted  into  sulphide  by  heating  it 
together  with  coal  in  a  revolving  furnace  at  1,100°  C. 

Sulphur  affords  one  of  the  most  interesting  examples 
of  substances  which  can  assume  a  number  of  varying  or 
so-called  allotropic  forms.  In  its  ordinary  form,  it  is  a 

30 


466  SULPHUR 

SULPHUR  (Continued)— 

yellow  crystalline  body  of  octahedral  formation,  but  by 
melting  it  under  certain  conditions  it  can  be  obtained  in 
the  form  of  prismatic  needles  of  transparent  character 
which  melt  at  119°  C.  and  upon  exposure  to  the  air,  gradu- 
ally lose  their  transparency,  crumble  up,  and  assume  once 
more  the  form  of  octahedra. 

The  influence  of  heat  upon  sulphur  is  remarkable.  The 
ordinary  rhombic  form  melts  at  about  112-8°  C.  to  a 
yellow,  limpid  (thinnish)  liquid ;  but  if  the  temperature  be 
allowed  to  rise  to  230°  C.,  it  becomes  quite  viscid  (thick) 
and  darkens  very  much  in  colour.  If  the  heat  be  still 
further  raised,  it  again  becomes  more  fluid,  but  not  so  fluid 
as  when  first  melted.  If,  when  in  the  viscous  state,  it  be 
allowed  to  cool  suddenly  (as  by  pouring  it  into  cold  water), 
it  solidifies  into  a  soft  mass  which  can  be  drawn  out 
into  elastic  threads  having  a  sp.  gr.  of  1-96,  whereas  the 
natural  crystals  of  sulphur  have  a  sp.  gr.  of  2-07.  This 
form  can  be  again  transformed  into  the  original  by  heating 
it  to  1 00°  C.,  when  it  suddenly  returns  to  the  brittle  con- 
dition with  an  evolution  of  heat.  This  change  also  takes 
place  if  it  is  kept  for  a  short  time. 

When  sulphur  is  distilled  in  small  quantities  and  the 
vapour  allowed  to  condense  in  a  vessel  not  artificially 
cooled,  it  takes  the  form  of  red  oily  drops  which  remain 
fluid  for  some  hours,  but  afterwards  pass  into  the  solid 
condition.  • 

These  changes  appear  to  be  due  to  varied  molecular 
arrangements  corresponding  to  environment.  Between 
117°  and  157°  C.  the  sulphur  molecule  appears  to  be  S6 
and  between  180°  and  445°  C.  S18. 

It  may  be  sublimed — that  is  to  say,  it  can  be  volatilized 
or  made  to  assume  the  form  of  vapour,  which  can  then  be 
condensed  into  the  solid  state. 

Sulphur  is  soluble  in  carbon  disulphide  (CS2),  and  can  be 
obtained  in  crystalline  form  therefrom.  It  is  marketed  in 
the  forms  of  crystals,  "  roll,"  "  precipitated,"  and  "  sub- 
limed." 

At  one  time,  sulphur  was  largely  used  in  the  making  of 
matches,  but  this  has  been  superseded  by  other  methods. 
It  is  used  in  the  manufacture  of  gunpowder  and  sulphuric 
acid,  also  in  vulcanizing  processes,  in  pharmacy  in  com- 
pounding so-called  milk  of  sulphur  and  other  medicaments, 
and  for  fumigating  beer  casks  and  infected  rooms. 

Sulphur  burns  in  the  air  with  a  blue  flame  and  gives  rise 
to  the  production  of  sulphur  dioxide  (SO2),  a  gas  of  pungent, 


SULPHUR  AND  ITS  COMPOUNDS  467 

SULPHUR  (Continued)— 

irritating  nature  which  may  be  condensed  and  liquefied,  or 
a  solution  of  it  in  water  can  be  prepared.  In  all  three 
forms  it  is  used  for  disinfecting  purposes  ;  also  for  bleach- 
ing straw,  silk,  wool,  and  sponge. 

Kingzett's  Sulphur  Candles,  for  fumigating  purposes, 
are  so  constructed  that  the  burning  of  the  sulphur  is  com- 
pletely ensured,  and  meanwhile  causes  the  simultaneous 
evaporation  of  water,  which  materially  assists  the  steri- 
lizing effects  of  the  generated  sulphur  dioxide. 

Sulphur  is  said  to  exercise  a  valuable  toxic  action  as  a 
fungicide  ;  for  example,  flowers  of  sulphur  applied  in  paste 
form  to  hot-  water  pipes  in  greenhouses  will  keep  in  check, 
diseases  of  the  mildew  type  on  plants  kept  in  the  houses. 

Sulphur  Oxides  —  Of  the  oxides  of  sulphur,  the  two  most 
important  are  the  gaseous  dioxide  (SO2)  (which  is  soluble 
in  water  to  the  extent  of  79*789  volumes  in  i  volume  at 
o°  C.),  and  the  trioxide  (SO3),  the  latter  being  produced 
when  a  mixture  of  SO2  and  oxygen  are  passed  over  strongly 
heated  spongy  platinum  (which  acts  as  a  catalytic  agent 
and  effects  their  combination)  in  the  form  of  white  silky 
needles  when  condensed  in  a  cooled  receiver.  It  is  a 
volatile  body  which  fumes  in  the  air,  melts"  at  14-8°  C., 
and  combines  eagerly  with  water,  forming  sulphuric  acid  — 


=  HaSO4. 

The  acids  formed  from  the  oxides  include  hyposulphur- 
ous,  sulphurous,  sulphuric,  and  thiosulphuric  acids.  Other 
combinations  are  known  as  dithionic  acid  (H2S2O6),  tri- 
thionic  acid  (H2S3O6),  tetrathionic  acid  (H2S4O6),  and 
pentathionic  acid  (H2S5O6). 

Hyposulphurous  (Hydrosulphurous)  Acid  (H2S2O4)  can  be 
made  from  sulphurous  acid  by  reduction  with  zinc,  when  the 
hydrogen  generated  in  a  nascent  state  is  not  evolved,  but 
combines  as  expressed  in  the  equation  — 

2H2S03+H2=H2S204  +  2H20. 

In  solution,  this  unstable  acid  exhibits  a  yellowish  colour 
and  considerable  bleaching  properties. 

Sulphurous  Acid  (H2SO3)  is  known  only  in  solution  and  is 
somewhat  unstable,  but  less  so  than  the  hyposulphurous 
acid.  It  has  a  strong  odour  of  sulphur  dioxide,  and 
gradually  undergoes  decomposition  by  absorption  of  at- 
mospheric oxygen.  Being  dibasic  in  character,  it  forms 
two  series  of  salts,  which  are  represented  by  potassium 


468  SULPHUR  AND  ITS  COMPOUNDS 

SULPHUR  (Continued)— 

hydrogen  sulphite,  or  acid  potassium  sulphite  (KHSO3),  and 
potassium  sulphite  (K2SO3).  The  various  sulphites  are 
crystalline  compounds  and  'are  obtained  by  the  interaction 
of  sulphur  dioxide  and  an  alkali  in  the  presence  of  water, 
a  hot  aqueous  solution  of  the  alkali  carbonate  being  treated 
with  the  SO2  gas  until  the  desired  salt  is  completely  formed 
in  solution  of  the  requisite  strength,  to  crystallize  out  on 
cooling.  The  calcium  salts  are  similarly  made,  using  calcium 
hydroxide  (Ca(OH)2)  or  the  carbonate  (CaCO3). 

Thiosulphuric  Acid  (H2S2O3)  is  not  known  in  the  free 
state,  being  of  very  unstable  character,  but  it  forms  well- 
defined  salts,  obtained  by  digesting  flowers  of  sulphur  in 
solutions  of  sulphites.  Of  these  the  sodium  compound, 
(Na2S2O3,5H2O),  incorrectly  known  as  sodium  hyposulphite 
(which  can  be  prepared  by  the  action  of  sulphur  dioxide  on 
sodium  sulphide  in  solution,  and  should  be  termed  sodium 
thiosulphate),  is  the  most  important.  It  is  a  crystalline 
body  very  soluble  in  water,  and  largely  used  in  photography 
in  the  process  known  as  "fixing  "  ;  also  as  an  "  antichlor." 

Sulphuric  Acid  (H2SO4),  or  ordinary  oil  of  vitriol,  is  one 
of  the  most  important  sulphur  compounds  and  is  manu- 
factured from  sulphur  dioxide  —  as  produced  by  the  roasting 
of  pyrites,  or  by  burning  sulphur  in  the  air  —  by  oxidation 
of  the  sulphur  dioxide  (SO2)  vapour  in  contact  with 
moisture  (water  vapour)  by  the  agency  of  gaseous  nitric 
peroxide,  thus  : 

2S02  +  2NO2  +  2H20  =  2H2SO4  +  2ND, 

the  sulphuric  acid  thus  produced  being  absorbed  or  dis- 
solved in  water.  In  other  words,  through  the  agency  of 
the  nitric  peroxide  the  SO2  is  made  to  take  up  an  extra 
atom  of  oxygen,  and  this,  in  combination  with  water, 
furnishes  sulphuric  acid  — 


The  nitric  peroxide  is  obtained  from  nitric  acid,  which 
in  turn  is  produced  by  the  action  of  strong  sulphuric  acid 
(H2SO4)  upon  sodium  nitrate  (NaNO3),  thus  : 

2NaNO3  +  H2S04  =  Na2SO4  +  2HNO3. 

In  this  process,  the  nitric  peroxide  (NO?)  gives  up  some 
of  its  oxygen,  being  reduced  to  nitric  oxide  (NO),  which 
becomes  peroxidized  again  by  the  air,  regenerating  the 
NO2,  to  serve  anew  the  same  purpose.  (See  Alkali  Trade.) 

In    the   practical  manufacture   of    sulphuric  acid,   the 


SULPHUR  AND  ITS  COMPOUNDS  469 

SULPHUR  (Continued)— 

gaseous  sulphur  dioxide  mixed  with  air  is  "  nitrated  "  by 
passing  the  mixture  up  what  is  known  as  a  "  Glover 
tower,"  in  which  it  encounters  a  stream  of  nitric  acid  or 
nitrated  sulphuric  acid  slowly  flowing  over  flints,  after 
which  it  is  passed  into  the  leaden  condensing  chambers 
into  which  steam  or  water  (in  the  form  of  fine  spray)  enters, 
and  in  which  the  sulphuric  acid  is  condensed.  The  current 
of  air  carrying  nitrous  gases  is  then  made  to  pass  up  what 
is  known  as  the  "Gay  Lussac  tower,"  where  it  encounters 
a  stream  of  sulphuric  acid  trickling  over  coke  packed  in 
the  tower,  with  the  result  that  the  nitrous  gases  are 
absorbed,  and  the  acid  so  charged  is  used  over  again  in  the 
"  Glover  tower." 

The  acid  prepared  in  this  way,  is  of  about  70  per  cent, 
strength  and  is  concentrated  by  evaporation  or  by  passage 
down  a  tower  in  the  form  of  fine  spray,  in  which  it 
encounters  a  current  of  hot  producer  gas  which  carries  off 
the  water,  the  concentrated  acid  being  collected  at  the 
base.  (See  also  Cottrell  Precipitating  Plant.) 

Oxidation  of  ammonia  as  a  means  of  supplying  the 
oxides  of  nitrogen  required  for  the  chemical  reactions  in 
the  chamber  process  of  sulphuric  acid,  has  come  into  use  in 
recent  years.  (See  Nitrogen  Fixation.) 

Fuming  Sulphuric  Acid  ("  Oleum  ")  is  really  a  solution  of 
sulphur  trioxide  (generally  about  10  per  cent.)  in  100  per 
cent.  H2SO4  and  is  now  made  on  a  rapidly  increasing 
scale  by  the  catalytic  or  contact  process,  as  referred  to 
already  under  Sulphur  Oxides.  Instead  of  using  a 
mixture  of  sulphur  dioxide  and  oxygen,  ordinary  sulphuric 
acid  can  be  employed.  This  is  split  up  by  great  heat  into 
water,  sulphur  dioxide,  and  oxygen  ;  the  water  is  removed 
and  the  remaining  fixed  gases  are  passed  over  ferric  oxide 
(which  effects  the  combination  to  the  extent  of  about  60  per 
cent.),  and  then  over  pumice-stone  coated  with  finely  divided 
platinum,  maintained  at  a  temperature  lower  than  that  used 
to  break  up  the  original  acid,  to  complete  the  combination 
into  the  tri-oxide  (SO3),  which  can  then  be  condensed  as 
such  or  in  sulphuric  acid  (as  made  by  the  ordinary  process) 
in  order  to  concentrate  it.  The  platinum  is  deposited  on 
the  pumice-stone  by  soaking  it  in  a  solution  of  platinum 
and  ammonium  chlorides  and  heating  to  dull  redness. 
(See  Nordhausen  Acid.) 

In  the  pure  state,  sulphuric  acid  is  a  heavy,  colourless, 
oily  body  of  very  corrosive  properties,  having  a  great 
affinity  for  water,  and  behaving  with  the  oxides  and 


470  SULPHUR  AND  ITS  COMPOUNDS 

SULPHUR  (Continued}— 

carbonates  much  in  the  same  way  as  hydrochloric  and 
nitric  acid,  forming  the  corresponding  sulphates.  The 
annual  production  of  the  various  forms  of  this  acid  in  the 
United  Kingdom  exceeds  4  million  tons,  and  it  finds 
employment  in  a  great  number  of  industrial  applications, 
such  as  the  manufacture  of  explosives,  dyes,  washing 
soda,  glucose,  ammonium  sulphate,  superphosphate  of 
lime,  etc. 

Sulphates  —  Sulphuric  acid  forms  several  definite  com- 
binations with  water  represented  by  the  formulae  H2SO4, 
H2O,  and  H2SO4,2H2O,  so  that  in  addition  to  the  ordinary 
sulphates  corresponding  to  H2SO4,  such  as  the  potassium 
salt  (K2SO4),  the  barium  salt  (BaSO4)  and  potassium 
hydrogen  sulphate  (KHSO4),  there  are  known  compounds 
corresponding  to  the  other  two  molecular  combinations. 

Hydrogen  Sulphide  or  Sulphuretted  Hydrogen  (H2S)  is 
an  offensive  smelling  gas  which  is  found  in  nature  in 
volcanic  areas  and  is  contained  in  many  mineral  waters, 
(such  as  Harrogate),  which  are  used  medicinally. 

It  can  be  prepared  by  the  action  of  dilute  hydrochloric  acid 
(or  sulphuric  acid)  upon  ferrous  sulphide  (see  p.  219)  — 


and  is  colourless,  poisonous,  soluble  in  water  (to  the  extent 
of  4-37  volumes  in  i  volume  water  at  o°  C.),  and  burns 
when  ignited,  producing  sulphur  dioxide  and  water  — 


It  forms  sulphides  by  its  action  on  many  metals,  oxides, 
and  metallic  salts,  and  tarnishes  many  metals  by  direct 
combination. 

The  sulphides  of  the  metals  of  the  alkalies  and  alkaline 
earth  groups  are  more  or  less  soluble  in  water,  but  the 
others  are  insoluble. 

There  is  a  process  in  use  for  the  recovery  of  the  sulphur 
in  alkali  waste  (based  upon  the  production  of  hydrogen 
sulphide)  by  its  treatment  when  mixed  into  a  paste 
with  water,  in  several  successive  vessels  with  carbon 
dioxide  or  lime-kiln  gas  (which  largely  consists  of  that 
body).  The  carbon  dioxide  at  first  decomposes  the  calcium 
sulphide  of  the  waste,  liberating  hydrogen  sulphide,  and 
this  passing  into  the  next  vessel  forms  soluble  calcium 
hydrosulphide,  which  in  turn  is  decomposed  by  carbon  di- 
oxide, so  that  a  series  of  interactions  is  involved  as  follows  : 


SULPHUR— SUMAC  471 

S  ULPHUR  ( Continued) — 

CaS  +  H2O  +  CO2       =  CaCO3  +  H2S 
CaS  +  H2S  =CaS2H2 

and  CaS2H2  +  CO2  +  H2O  =  CaCO3  +  2H2S, 

the  sulphuretted  hydrogen  so  generated,  although  mixed 
with  atmospheric  nitrogen  and  some  carbon  dioxide,  being 
rich  enough  to  burn  into  sulphur  dioxide,  which  is  then 
utilized  for  making  sulphuric  acid  or  otherwise. 

Sulphur  Chlorides — Sulphur  and  chlorine  in  interaction 
yield  two  interesting  bodies  with  the  formulae  S2C12  (di- 
sulphur  dichloride)  and  SC12  (sulphur  dichloride) ;  the  first 
is  formed  by  passing  a  stream  of  dry  chlorine  gas  over 
heated  sulphur,  when  the  dichloride  distils  over  as  an 
amber-coloured  volatile  liquid  of  unpleasant  irritating 
odour.  The  other  is  produced  by  the  same  "process  con- 
ducted at  a  temperature  not  above  o°,  and  is  also  a  dark 
reddish  liquid  (much  less  stable  than  the  dichloride),  which 
has  the  property  of  dissolving  sulphur  with  avidity,  thus 
yielding  a  liquid  used  in  vulcanizing  rubber,  etc. 

Sulphur  Oxychlorides  number  four  compounds  having  the 
formulae  SOC12,  SO2C12,  SO2C1(HO),  and  S2O5C12.  The 
second  of  these  compounds,  known  variously  as  sulphuryl 
chloride  and  chloro-sulphuric  acid,  is  formed  by  the  direct 
union  of  chlorine  and  sulphur  dioxide  in  bright  sunshine 
and  can  be  otherwise  prepared.  It  is  a  colourless  liquid  of 
sp.  gr.  i '66  which  fumes  in  moist  air,  and  boils  at  70°  C. 

Carbon  Disulphide  (CS2)  is,  in  the  pure  state,  a  colourless, 
heavy,  but  mobile  liquid  of  high  refractive  character  and 
sweetish  smell,  but  as  usually  prepared  it  has  a  most  un- 
pleasant odour.  It  is  very  poisonous,  highly  inflammable, 
has  a  sp.  gr.  of  1-292  at  o°,  boils  at  46°  C.,  and  is  largely 
used  as  a  solvent.  (See  p.  88.) 

SULPHURETTED  HYDROGEN— See  p.  470. 
SULPHURIC  ACID— See  p.  468. 
SULPHURIC  ACID  TUBE— See  Drying  Tube. 
SULPHUROUS  ACID— See  p.  467. 

SULPHYDRATES  (Hydrosulphides)— Potassium  hydrosulphide 
is  KHS  and  calcium  hydrosulphide  is  CaH2S2.  (See 
Hydrosulphides,  p.  258.) 

SUMAC — A  tanning  material  in  the  form  of  a  powder  prepared 
from  the  dried  leaves  and  twigs  of  various  shrubs  and  trees 
of  the  Rhus  order.  It  is  also  used  in  dyeing  and  calico- 
printing. 


472  SUNFLOWER  OIL-SYLVESTRENE 

SUNFLOWER  OIL  (from  Helianthus  annus)  is  a  pale  yellow 
liquid  of  sp.  gr.  0-924,  with  a  saponification  value  of 
189  to  193,  refractive  index  of  1*461,  and  iodine  value 
129  to  132;  soluble  in  alcohol,  ether,  etc.  It  is  pro- 
duced in  Russia  on  a  considerable  scale,  some  2,700 
square  miles  being  devoted  to  its  cultivation.  It  is  also 
produced  in  China,  Italy,  and  India.  The  seeds  yield  about 
20  to  23  per  cent,  of  the  oil,  which  is  said  to  be  as  good  as 
olive  oil  for  edible  purposes,  and  is  used  in  making  soaps, 
varnishes,  and  illuminants.  It  is  a  slow-drying  oil,  and 
contains  the  glycerides  of  oleic,  linolic,  and  palmitic  acids. 

"  SUPERB ASIQUE  METAL"— A  modification  of  cast  iron, 
having  a  greater  resistance  to  the  action  of  alkaline 
solutions. 

" SUPERNEUTRAL  METAL"— A  silicon-iron  alloy  suitable 
for  the  construction  of  nitric  acid  condensers,  etc. 

SUPERPHOSPHATE  OF  LIME  is  an  admixture 'of  soluble  acid 
phosphate  of  calcium  (CaH4(PO4)2),  and  is  prepared  in 
large  quantities  for  use  as  a  fertilizer  by  treating  phos- 
phates (such  as  sombrerite,  apatite,  and  coprolites),  bones, 
etc.,  with  about  two-thirds  of  their  weight  of  sulphuric  acid 
of  sp.  gr.,  1-55  to  i -60.  The  mixture  thus  produced,  is 
one  of  calcium  sulphate  with  calcium  monophosphate — 

(Ca3(PO4)2  +  2H2SO4  =  2CaS04  +  CaH4(PO4)2, 

but  if  a  larger  quantity  of  sulphuric  acid  is  used  the  phos- 
phate is  converted  into  tribasic  phosphoric  acid,  so  that  the 
product  is  of  varying  composition. 

Bone  charcoal,  which  has  been  used  for  decolourizing 
purposes  as  ordinarily  prepared,  viz.,  by  charring  bones, 
still  retains  its  calcium-phosphate  constituents,  and  can  be 
utilized  by  this  method  for  the  production  of  "  super- 
phosphate," the  total  consumption  of  which  amounted  in 
the  United  Kingdom  to  750,000  tons  in  1919. 

There  are  many  grades  of  phosphates  manufactured  as 
fertilizers.  The  free  phosphoric  acid  in  a  good  super- 
phosphate should  amount  to  less  than  i  per  cent.,  and  the 
water  should  not  exceed  10  to  12  per  cent. 

The  strength  is  expressed  in  percentage  of  P2O5  soluble 
in  water  and  in  ammonium  citrate,  but  80  per  cent,  should 
be  soluble  in  water. 

SYLVANITE— A  gold,  silver,  and  tellurium  ore  ((Ag,Au)Te2) 
found  in  Transylvania,  Colorado,  and  elsewhere. 

SYLVESTRENE  (C10H16)— A  terpene,  which  boils  at  175°  C, 
and  is  the  chief  constituent  of  genuine  Russian  and  Swedish 


SYLVESTRENE—TAIFUSHI  OIL  473 

SYLVESTRENE  (Continued)- 

turpentine  oils.  It  gives  a  fine  blue  coloration  with  acetic 
anhydride  and  strong  sulphuric  acid.  (See  Essential  Oils 
and  Terpenes.) 

SYLVIC  ACID— A  reputed  constituent  of  rosin. 

SYLVINITE— See  Potassium. 

SYMBOLS — See  Elements,  Chemical  Interactions,  and  Formulae. 

SYMPATHETIC  INK— See  Inks  and  Cobalt. 

SYNAPTASE  (Emulsin)— See  Amygdalin. 

SYNTHESIS — The  building  up,  by  chemical  means,  of  elements 
into  compounds,  or  of  compound  bodies  into  more  complex 
bodies — in  other  words,  the  reverse  of  analysis  or  decom- 
position. 

The  production  of  rust  upon  iron  is  an  act  of  synthesis, 
by  which  the  oxygen  and  other  constituents  of  the  air  enter 
into  chemical  combination  with  the  iron  ;  and  the  formation 
of  verdigris  on  copper  exposed  to  damp  air  is  another  act 
of  synthesis. 

When  hydrogen  gas  is  burned  in  the  air  it  forms  water 
synthetically,  by  chemical  combination  with  the  atmospheric 
oxygen. 

When  lime  is  heated  to  a  certain  temperature  in  a 
current  of  carbon-dioxide  gas,  they  enter  into  combination, 
forming  calcium  carbonate  by  synthesis. 

Chemists  have  succeeded  in  synthetically  building  up 
many  very  complex  substances,  amongst  others  urea, 
acetic  acid,  acetylene,  alcohol,  salicylic  acid,  alizarin, 
indigotin,  etc. 

SYNTONIN — A  peptone  prepared  from  muscle  fibrin  by  the 
action  of  dilute  hydrochloric  acid. 

TAIFUSHI  OIL — The  Oleum  gynocavdice  (Oleum  chaulmoogra) 
of  the  Japanese  pharmacopoeia,  contains  as  its  chief  con- 
stituents glyceryl  chaulmoograte  and  hydnocarpate,  and 
some  palmitin,  and  is  surmised  to  be  obtained  from  the 
seeds  of  Hydnocarpus  anthelmintica  (not  from  Taraktogenos 
Kurzii,  which  is  the  source  of  the  genuine  chaulmoogra  oil) . 
Its  sp.  gr.  is  0-952  ;  it  melts  at  22°  C. ;  its  saponification 
number  is  20-30,  and  iodine  number  85-05. 

Pure  chaulmoogric  acid  (C18H32O2)  melts  at  68°  C., 
has  an  iodine  value  of  90-1,  and  specific  rotation  of  +56°; 
and  pure  hydnocarpic  acid  (C16H28O2)  melts  at  59°  C., 
has  an  iodine  value  of  100*2,  and  specific  rotation  +68*1°. 
(See  Chaulmoogra  Oil.) 


474  TALC— TANNING 

TALC — A  very  widely  diffused  mineral,  partly  composed  of 
hydrous  magnesium  silicate.  One  published  analysis 
gives— 

SiO2       ...  ...  ...     63-2  per  cent. 

MgO      ...  ...  ...     28-0 

Moisture,  etc.       ...  ...       8-8       „ 


i  oo-o 

The  more  laminated  varieties  are  of  considerable  utility  for 
making  stove-windows,  goggles,  lamp  chimneys  and  phono- 
graph diaphragms,  being  transparent  and  incombustible. 
The  world's  production  in  1918  amounted  to  296,478  metric 
tons.  Talc  powder  forms  a  very  nice  absorbent  basis. 
(See  also  French  Chalk,  Mica,  Soap-Stone,  and  Steatite.) 

TALLOW — The  name  applied  to  the  harder  varieties  of  fats, 
such  as  the  suet  of  the  ox  and  sheep  and  the  vegetable  cacao 
fat.  It  is  separated  from  the  cellular  tissue  with  which  it 
is  associated  in  suet,  by  melting. 

Beef  tallow  has  a  sp.  gr.  of  0-943  to  °'952J  a  saponifica- 
tion  value  of  193  to  200,  and  an  iodine  value  of  38  to  46. 

Mutton  tallow  has  a  sp.  gr.  of  0-937  to  °'953>  a  saponi- 
fication  value  of  192  to  195,  and  an  iodine  value  of  35  to  46. 

Tallow,  like  other  fats,  consists  of  a  mixture  of  stearin, 
palmitin,  and  olein,  in  which  the  harder  fats  predominate. 

There  is  another  vegetable  tallow,  which  is  extracted 
from  the  fruit  o'f  the  Chinese  tallow-tree,  which  is  also 
used  in  soap-making.  (See  Fats.) 

TANNIC  ACID  or  GALLIC  ACID  (C7H6O6)  is  practically  another 
name  for  tannin,  but  it  would  appear  that  there  are  a 
number  of  tannic  acids  nearly  related  but  differing  to  some 
extent  according  to  their  source — e.g.,  kino-tannin,  catechu- 
tannin,  coffee-tannin,  sumac,  etc.  Gallo-tannic  acid  (see 
Gall  Nuts)  is  a  colourless  amorphous  substance  readily 
soluble  in  water  and  yields  gallic  acid  when  boiled  with 
dilute  acids.  A  commercial  tannic  acid  is  prepared  of  55  to 
58  per  cent,  strength.  (See  Gallic  Acid.) 

TANNING  is  an  important  industry,  as  indicated  by  the  fact 
that  in  1918  about  8  million  hides  and  calf  skins  of  the 
value  of  ^"30,000,000  were  tanned  in  the  United  Kingdom. 
After  soaking  to  remove  blood  and  lymph,  the  skins  are 
painted  on  the  fleshy  side  with  a  mixture  of  slaked  lime 
and  sodium  sulphide  or  calcium  hydrosulphide,  and  then 
the  wool  is  pulled,  leaving  the  skin,  or  "  pelt."  This,  after 
washing,  is  passed  through  a  lime  liquor,  and,  after  rubbing 


TANNING— TANNINS  475 

TANNING  (Continued)— 

off  the  hair,  is  then  subjected  to  a  mechanical  operation 
(fleshing)  to  remove  all  adhering  flesh,  when  the  skins  are 
ready  for  "  bating,"  or  "  puering,"  to  render  them  soft 
and  supple  by  removal  of  hair  sheaths,  sebaceous  glands, 
muscles,  sweat  ducts,  etc.,  held  together  by  elastic  fibres — 
a  process  which  is  of  a  fermentative  character,  carried  out 
by  dressing  with  dung.  After  drenching,  the  skins  are 
then  ready  for  treatment  with  the  tan  liquor,  which  may  be 
an  infusion  of  sumac  ;  other  tanning  materials  being  barks, 
gambier,  myrobalans,  valonia,  and  extracts,  such  as  kino, 
and  those  of  oakwood,  chestnut,  and  quebracho. 

In  the  process  of  tanning,  the  astringent  principles  enter 
into  combination  with  the  collagen  (gelatinous  or  proteid) 
part  of  the  skins  constituting  the  fibrous  tissues,  producing 
leather. 

Formaldehyde  has  been  used  in  tanning,  by  reason  of 
its  coagulating  and  preservative  effect  on  the  collagen 
molecule. 

In  another  process  of  tanning,  chromium  salts  are  used 
for  treatment  of  the  prepared  pelts,  the  bath  consisting 
of  a  mixture  of  potassium  or  sodium  dichromate  with 
hydrochloric  or  sulphuric  acid,  followed  by  the  application 
of  sodium  thiosulphate  to  effect  the  reduction  of  the 
chromium  salt  to  a  basic  state  or  oxide  in  combination 
with  the  tissue.  It  is  stated  that  after  unhairing  and  pick- 
ling by  immersion  in  a  bath  of  dilute  sulphuric  acid  and 
sodium  chloride,  skins  can  be  completely  tanned  in  two 
days  by  immersion  in  a  bath  of  chrome  liquor,  consisting 
of  basic  chromic  sulphate  diluted  to  contain  17  grms.  of 
chromic  oxide  per  litre.  The  impregnation  of  the  materials 
to  be  tanned  is  sometimes  effected  by  a  process  of  electric 
endosmose,  which  is  said  to  be  applicable  to  the  impregna- 
nation  with  chromium  or  other  metallic  salts,  of  fabrics 
which  have  been  treated  with  glue  or  gelatin,  and  that 
this  method  permits  of  the  utilization  of  very  dilute  tanning 
liquors  and  greatly  facilitates  the  process  in  point  of  time. 

TANNINS — Astringent  principles  of  the  bark  and  some  other 
parts  of  certain  trees  (such  as  the  chestnut,  oak,  hemlock, 
larch,  quebracho,  osage,  mimosa,  sumac,  and  eucalyptus) 
which  combine  with  albumen  and  gelatine,  as  occurring 
in  animal  hides,  to  form  leather.  In  Australia,  wattle  bark 
is  the  principal  tanning  agent  employed  by  tanners,  that  of 
the  golden  wattle  (Acacia  pycnantha)  and  the  black  or  green 
wattle  (A.  decurrens)  being  two  of  the  more  important 


476  TANNINS— TAR  ACIDS 

TANNINS  (Continued)— 

varieties.  A  valuable  tan  bark  is  yielded  by  the  mallee 
(Eucalyptus  Occident alis).  The  astringent  principle  common 
to  cutch  and  mimosa  extract  is  either  a  glucoside  or 
associated  with  a  substance  of  that  nature,  as  they  both 
yield  an  unfermentable  sugar  upon  hydrolysis.  It  has 
become  customary  to  determine  as  tannin  that  portion  of 
the  water-soluble  constituents  of  vegetable  materials  which 
will  precipitate  gelatin  from  solution,  and  which  will  form 
compounds  with  hide  fibre,  which  are  resistant  to  washing. 
(See  Cutch,  Gambier,  Mimosa,  Sumac,  and  Gall  Nuts.) 

TANSY  OIL — Distilled  from  the  herb  Tanacetum  vulgare,  and 
containing  thujone,  camphor,  borneol,  etc.  It  is  a  yellowish, 
thin  oil  of  poisonous  character,  which  rapidly  darkens  upon 
exposure  to  the  air  ;  is  soluble  in  alcohol  and  ether ;  has  a 
sp.  gr.  of  0*925  to  0-955  5  and  is  usec^  m  medicine  and  per- 
fumery. 

TANTALITE — A  rare  mineral,  consisting  of  iron  and  man- 
ganese tantalate  ((FeMn)Ta2O6),  generally  containing  some 
columbium. 

TANTALUM  (Ta)— Atomic  weight,  181-5;  sp.  gr.,  16-8.  Tanta- 
lum is  a  rare  metallic  element  found  in  nature  in  association 
with  another  rare  element  (niobium)  in  a  number  of  Austra- 
lian and  Swedish  minerals,  including  columbite  and  tantalite. 
It  is  a  little  darker  than  platinum;  is  nearly  related  to 
vanadium ;  has  a  very  high  melting-point — about  2,900°  C. ; 
and  is  chiefly  used  in  making  electric  lamp  filaments.  It  is 
not  attacked  by  acids ;  it  combines  with  carbon  to  form 
carbides,  and  at  a  red  heat  combines  with  hydrogen, 
nitrogen,  and  chlorine.  Two  insoluble  oxides  (Ta2O4  and 
Ta2O5)  are  known,  and  a  number  of  compounds  corre- 
sponding to  the  phosphates.  The  metal  is  made  by  heating 
the  double  fluoride  of  tantalum  and  potassium  in  an  electric 
furnace. 

"TANTIRON"— A  hard  and  brittle  brand  of  acid-resisting 
silicon-iron  alloy. 

TAPIOCA — A  starchy  body,  useful  as  food,  obtained  from  the 
roots  ofjanipha  Manihot,  cultivated  in  the  West  Indies. 

TAR— See  Coal  and  Wood. 

TAR  ACIDS — A  common  designation  for  mixtures  of  phenol 
(carbolic  acid)  with  cresols,  and  used  in  respect  of  all  con- 
stituents of  such  liquids  as  may  be  combined  with  and 
extracted  by  means  of  caustic  soda  or  other  alkali.  (See 
Carbolic  and  Cresylic  Acids.) 


TARAXACUM  OFFICINALE— TEA  477 

TARAXACUM  OFFICINALE  or  DANDELION— Extract  or  in- 
fusion of  dandelion  (Leontodon  taraxacum),  containing  an 
active  principle  named  taraxacin,  and  used  as  a  laxative. 

TARRAGON  OIL— A  nearly  colourless  liquid,  distilled  from 
Artemisia  dracunculus -,  sp.  gr.,  0*900  to  0^949;  optical 
rotation,  +  2  to  +  9 ;  and  refractive  index,  1*5161  to  1*517 ; 
soluble  in  alcohol  and  ether,  and  used  in  medicine  and 
for  flavouring, 

TARTAR — A  name  applied  generally  to  salts  of  tartaric  acid, 
but  more  particularly  to  the  acid  potassium  tartrate 
(KHC4H4O6)  which  is  deposited  from  fermenting  grape 
juice  and  wines  on  long  keeping.  This  is  known  in  com- 
merce as  "crude  tartar  "  or  "argol,"  and  gives  "cream  of 
tartar"  when  purified  by  being  dissolved  in  water  and  re- 
crystallized. 

TARTAR  EMETIC — See  Antimony,  p.  35. 

TARTARIC  ACID  (C4H6O6)  occurs  in  nature  either  in  the  free 
state  or  in  combination  with  potassium  and  calcium  as 
tartrates,  in  many  vegetable  juices  such  as  tamarinds, 
girkins,  mulberries,  pineapples,  and  more  particularly  in 
grape  juice  in  combination  as  acid  tartrate  of  potassium. 
(See  Tartar.)  It  is  readily  prepared  in  a  crystalline  state 
from  the  last-named  substance  or  crude  argols.  (See 
Argol.) 

Tartaric  acid  crystallizes  in  large  prisms,  which  are 
soluble  in  water.  It  fuses  at  170°  C. ;  is  decomposed  at 
1 80°  C. ;  and  is  used  in  calico-printing  as  a  solvent  for  the 
mordant  and  finds  applications  in  medicine. 

Tartaric  acid  is  known  in  four  distinct  modifications. 
(See  Racemic  Acid.) 

TAURINE  (C2H7NSO3) — A  crystalline  body  somewhat  soluble 
in  water,  found  present  in  the  faeces  and  easily  obtained  by 
the  action  of  acids  upon  bile. 

TAURpCHOLIC  ACID  (C«6H45NSO7)— A  constituent  of  bile 
which  is  decomposed  by  boiling  with  acids,  yielding  cholic 
acid  and  taurine : 

C26H45NSO7  +  H2O  =  C^H^Og  (cholic  acid)  + 

C2H7NSO3  (taurine). 
(See  Bile.) 

TEA — The  dried  leaves  of  the  tea-plant  Thea  sinensis,  which  is 
largely  cultivated  in  China,  Japan,  India,  and  Ceylon.  It 
contains  an  essential  oil  (which  gives  aroma  to  it),  an  active 
principle  named  theine  or  caffeine  (C8H10N4O2),  legumin 


47&  TEA— TELLURIUM 

TEA  (Continued)— 

and  tannin,  in  varying  proportions  according  to  the  nature 
of  the  tea  and  other  circumstances  attending  its  production. 
The  amount  of  theine  varies  between  £  and  i\  per  cent., 
the  tannin  between  12  and  15  per  cent.,  and  the  essential 
oil  from  J  to  i  per  cent. 

Taken  in  moderation,  tea  is  a  useful  stimulant. 

TEA-SEED  OIL  is  expressed  from  the  seeds  of  Camellia  theifera, 
and  is  a  clear,  straw-coloured,  yellowish  oil,  without  odour 
or  taste,  closely  resembling  olive  oil,  for  which  it  is  used 
as  an  adulterant,  although  owing  to  the  presence  of  a 
poisonous  saponin  body,  it  has  been  condemned  as  an 
edible  oil.  Although  botanically  related  to  the  plant  from 
which  tea  is  prepared,  the  two  things  are  quite  distinct. 

There  are  several  varieties  on  the  market,  and  the 
Sasanqua  oil  has  a  sp.  gr.  of  0*916  to  0*919,  a  saponifica- 
tion  value  of  about  193*4  to  194,  and  an  iodine  value 
of  817  to  82*3. 

The  Thea  japonica  yields  Tsubaki  oil,  which  is  very 
similar  to  tea-seed  oil. 

TELEGRAPH— See  Electricity. 
TELEPHONE— See  Electricity. 

TELESCOPE — An  instrument  formed  of  several  lenses  so 
arranged  as  to  magnify  distant  objects, 

TELLURIUM  (Te)— Atomic  weight,  127*5;  SP-  gr->  6<25  5 
melting-point,  525°  C.  An  element  which  occurs  natur- 
ally to  some  small  extent  in  pure  crystalline  form,  but  is 
for  the  most  part  met  with  in  combination  in  some  rare 
minerals  including  telluvite  (TeO2),  tetradymite  (bismuth 
telluride,  Bi2Te3),  and  sylvanite  ((Ag,Au)Te2).  It  is  also 
said  to  exist  in  mineral  forms  associated  with  gold  in 
Hungary  and  Transylvania. 

It  is  a  bright  white  metal  of  lustrous  appearance  which 
is  soluble  in  nitric  and  sulphuric  acids  and  potassium 
hydroxide.  It  is  a  poor  conductor  of  heat  and  electricity, 
and  when  heated  in  the  air,  burns  with  a  blue  flame,  forming 
the  dioxide  (TeO2). 

The  metal  can  be  prepared  from  bismuth  telluride 
(Bi2Te3)  by  fusion  with  sodium  carbonate  and  carbon 
and  treatment  of  the  resulting  product  with  water,  which 
gives  a  solution  of  sodium  telluride  and  sodium  sulphide,  • 
and  upon  exposure  to  the  air  the  metallic  tellurium  is 
deposited  as  a  grey  powder,  which  can  be  purified  by  dis- 
tillation in  a  current  of  hydrogen  gas.  It  is  also  obtained 


TELLURIUM— TERPENES  479 

TELLURIUM  (Continued)— 

by   reduction   of    tellurium   dioxide.      It   is   used   in   the 
ceramic  industries. 

In  combination  with  hydrogen  it  forms  hydrogen  telluride 
(H2Te),  an  offensive  poisonous  gas  soluble  in  water  which 
is  decomposed  by  heat  and  deposits  metallic  tellurium  as  a 
crystalline  sublimate. 

Two  oxides  are  known  (TeO2  and  TeO3)  and  two  cor- 
responding acids,  known  as  tellurous  (H2TeO3)  and  telluric 
(H2TeO4)  acids,  analogous  to  sulphurous  and  sulphuric 
acids. 

Two  chlorides  are  known  (TeCl2  and  TeCl4)  and  cor- 
responding bromides  and  iodides. 

It  will  be  seen  that  in  general  properties,  tellurium  re- 
sembles sulphur  and  selenium. 

TEMPERATURES  (Notable)— See  Heat,  p.  242. 

TEMPERING — The  tempering  of' steel  is  brought  about  by 
heating  and  slow  cooling. 

TENSION  (of  Gases) — The  force  with  which  the  particles  or 
molecules  tend  to  recede  apart  and  to  occupy  a  greater 
space.  (See  Gases.) 

TERBIUM  (Tb) — Atomic  weight,  159-2.  A  rare  element 
contained  in  gadolinite,  samarskite,  euxonite,  and  monazite. 
Two  oxides  (Tb203  and  Tb4O7),  a  sulphate  (Tb2(SO4)3), 
chloride  (TbCl),  and  nitrate  (Tb(NO3))  are  known,  the 
salts  being  hygroscopic  and  crystalline. 

TEREBENE — American  or  French  turpentine  after  heating 
moderately  with  several  successive  small  quantities  of 
strong  sulphuric  acid  until  its  action  on  polarized  light 
is  quite  destroyed,  and  then,  after  washing,  submitted  to 
distillation.  It  is  a  mixture  of  hydrocarbons,  of  which 
inactive  camphene  is  one  and  dipentene  (C5H8)  another. 

TEREPHTHALIC  ACID  (C6H6O4)— An  oxidation  product  of 
turpentine  and  cymene,  nearly  insoluble  in  water  and 
alcohol,  which  sublimes  unchanged. 

TERPENES  (C10H16) — A  series  of  isomeric  liquid  hydrocarbons 
of  the  formula  C10H16,  having  boiling-points  ranging  from 
160°  to  190°  C.,  but  as  they  exist  in  essential  or  ethereal 
oils  they  are  mixtures  of  terpenes  and  not  chemical  indi- 
viduals, and  are  often  associated  with  oxidized  bodies  allied 
to  and,  in  many  cases,  derived  from  them.  Pinene  (dextro- 


48o  TERPENES-TERPINENE 

TERPENES  (Continued)— 

pinene)  is  the  chief  terpene  contained  in  the  American  and 
German  turpentine  oils,  laevo-pinene  is  the  chief  constituent 
of  French  turpentine,  whilst  sylvestrene  and  hemi-terpene, 
or  dipentene  (C5H8),  together  with  pinene,  are  contained 
in  varying  proportions  in  the  Russian  and  Swedish  oils. 
Indian  turpentine  contains  pinene  and  two  new  terpenes 
named  carene  and  longifolene.  Oil  of  orange  contains 
limonene.  Fennel  oil  and  some  eucalyptus  oils  contain 
phellandrene. 

Dextro-pinene  rotates  the  polarized  ray  to  the  right  and 
laevo-pinene  to  the  left. 

Citrene  is  contained  in  the  oil  of  citron,  hesperidene  in 
the  oil  of  orange,  thymene  in  the  oil  of  thyme,  carvene 
in  the  oil  of  cumin,  and  these  terpenes  have  the  formula 
C10H16,  and  approximately  the  same  boiling-point — viz., 
1 60°  to  190°  C. ;  but  for  the  most  part  they  are  mixtures  of 
isomeric  compounds,  and  all  are  liquid  with  the  exception 
of  camphene. 

The  terpenes  form  additive  compounds,  such  as  the 
dihydrochlorides,  C10H18C12 ;  tetrabromides,  C10H16Br4 ; 
nitroso-chlorides,  C^K^MOd)^  etc.,  most  of  which  are 
well-defined  crystalline  compounds  with  definite  melting- 
points. 

All  the  terpenes  also  yield  peroxide  of  hydrogen  when 
air-oxidized  in  the  presence  of  water. 

Isoprene  is  the  best-known  hemi-terpene  (C5Hg),  whilst 
dipentene  is  associated  with  cineol  in  Oleum  cina,  and  can 
be  easily  prepared  from  pinene  and  some  other  terpenes. 

These  compounds  are  further  referred  to  in  the  descrip- 
tions of  the  various  essential  oils  in  which  they  occur  or 
under  their  distinct  names. 

Another  associated  class  of  hydrocarbons  Oi  the  formula 
Ci5H24  are  termed  "  sesquiterpenes."  (See  also  Essential 
Oils.) 

TEEPIN  HYDRATE  (C10H2aO3  or  C;0H20O2,H2O)  is  a  colour- 
less, crystalline  substance  which  is  soluble  in  alcohol  and 
ether,  melts  at  116°  C.,  and  is  a  combination  of  water 
with  a  substance  named  terpin,  which  in  its  turn  is  pre- 
pared by  boiling  terpineol  (C10H18O)  with  dilute  sulphuric 
acid.  It  is  prepared  from  oil  of  turpentine  by  the  action 
of  an  alcoholic  solution  of  nitric  acid. 

TERPINENE— A  terpene  (C10H16)  obtained  by  the  action  of 
alcoholic  sulphuric  acid  on  dipentene.  It  boils  at  179°  C., 
and  is  optically  inactive. 


TERPINEOL—THA  LLI UM  48 1 

TERPINEOL  (C10H18O  or  C10H17OH)  is  a  kind  of  liquid 
alcohol  allied  slightly  in  chemical  nature  to  menthol  and 
carvone,  the  last-named  substance  being  the  chief  con- 
stituent of  the  oil  of  caraway-seeds.  It  is  stereo-isomeric 
with  geraniol,  and  occurs  naturally  to  some  extent ;  is 
readily  made  from  terpin  hydrate  by  the  action  of  dilute 
acid,  and  is  extensively  used  in  the  synthetic  perfumes 
industry,  being  the  basis  of  the  lilac  and  lily  artificial  pro- 
ducts. It  melts  at  37°  C.,  boils  at  210°  C.,  and  is 
soluble  in  alcohol  and  ether. 

TERPINOLENE— A  terpene  which  boils  at  183°  to  185°  C. 

TERRA  ALBA  of  commerce  is  variously  kaolin,  gypsum, 
burnt  alum,  or  magnesia,  but  the  term  should  be  reserved 
for  kaolin. 

TERRA  GOTTA— Baked  earth  or  clay. 

TEST-PAPERS — Absorbent  papers  impregnated  with  litmus 
for  testing  alkalinity  or  acidity  of  fluids.  (See  Litmus  and 
Turmeric  Paper.) 

TEST-TUBES  are  thin  glass  tubes  of  special  quality  and 
various  diameters  ranging  from  about  J  inch  to  i  inch, 
sealed  at  the  lower  end,  and  sometimes  provided  with  a  lip 
at  the  upper  end.  (Illustrations  of  them  will  be  found 
under  the  headings  of  Pneumatic  Trough  and  Voltameter.) 
They  are  chiefly  employed,  as  implied  by  their  name,  for 
making  chemical  tests,  and  are  capable,  when  containing 
liquids,  of  withstanding  the  direct  application  of  flame, 
such  as  that  of  a  Bunsen  burner. 

TETRADYMITE— See  Bismuth. 

TETRAHEDRITE  (Grey  Copper  Ore) — A  mineral  compound 
of  copper-antimony  and  other  sulphides  containing  about 
52  per  cent,  of  copper. 

"TETRALIN"  (Tetra-hydro-naphthalene  C10H12)—A  liquid 
of  pungent  odour  produced  by  the  hydrogenization  of 
naphthalene  in  the  presence  of  a  catalyst  and  used  as  a 
solvent  of  waxes,  resins,  rubber,  etc.,  and  substitute  for 
turpentine  in  varnish  and  polish  making.  (Compare 
"  Dekaline.") 

TETRATHIONIC  ACID— See  Sulphur  (Oxides). 

THALLIUM  (Tl)  and  its  Compounds — Atomic  weight,  204 ; 
sp.  gr.,  11-85;  melting-point,  294°  C.  An  element  present 
in  many  varieties  of  iron  and  copper  pyrites  so  that  it  can 
be  obtained  from  the  dust  resulting  from  the  roasting  of 


482  THA  LL1 UM—THEINE 

THALLIUM  (Continued)— 

pyrites  when  used  for  the  manufacture  of  sulphuric  acid. 
In  a  recently  reported  case,  4  Ibs.  of  thallium  was  recovered 
from  1,500  tons  of  pyrites,  the  dust  containing  0^25  per 
cent.,  equal  to  i  part  thallium  per  1,000,000  parts  of 
pyrites.  It  is  also  found  in  association  with  copper, 
selenium,  and  silver  in  the  rare  mineral  named  crookesite. 
It  is  obtained  from  the  sulphate  by  dipping  strips  of  zinc  in 
the  solution,  when  the  thallium  is  deposited  upon  the  zinc 
in  the  form  of  a  spongy  crystalline  mass ;  also  by  treating 
thallium  iodide  with  metallic  sodium.  It  is  bluish-white  in 
colour,  soft,  heavy,  soluble  in  nitric  and  sulphuric  acids, 
makes  a  mark  on  paper  as  lead  does,  and  is  intermediate 
in  properties  between  lead  and  the  alkaline  metals.  By 
reason  of  the  fact  that  it  undergoes  oxidation  in  the  air  to 
black  thallous  oxide,  it  has  to  be  preserved  in  water  to  keep 
its  normal  bluish-white  lustre. 

There  are  two  oxides,  thallous  oxide  (T12O)  and  thallic 
oxide  (T1^O3),  the  latter  being  a  dark  reddish  powder, 
insoluble  in  water,  formed  when  the  metal  is  melted  in 
presence  of  air. 

Thallous  Hydroxide  (T1HO)  is  produced  by  dissolving 
thallous  oxide  in  water,  or  by  adding  a  solution  of  barium 
hydroxide  to  one  of  thallous  sulphate,  and  concentrating 
the  filtrate  from  the  precipitated  barium  sulphate.  It  then 
crystallizes  in  yellow  needle-shaped  form.  It  is  soluble  in 
water  and  alkaline  in  reaction. 

Thallous  Chloride  (T1C1) — A  white  soluble  substance 
formed  when  metallic  thallium  is  heated  (when  it  burns)  in 
chlorine  gas  ;  and  there  is  another  chloride  (TC13),  a  colour- 
less body  obtained  by  passing  chlorine  through  water  con- 
taining thallous  chloride  in  suspension,  and  concentration 
of  the  resulting  solution,  when  it  crystallizes  out  in  com- 
bination with  water  (T1C13,2H2O). 

Thallous  Carbonate  (Tl2COy)  is  a  crystalline  body  soluble 
in  water. 

Thallous  Phosphate  (T13PO4)  is  obtained  by  precipitating 
a  thallous  solution  with  one  of  potassium  phosphate. 

The  Sulphide  (T12S)  is  an  insoluble  black  compound. 
THEBAINE  (Para-morphine)  (C19H21NO3)  an  alkaloidal  base, 
being   morphine   in   which   both    phenolic    and   alcoholic 
hydroxyls  are  methylated.     It  is  a  white,  crystalline,  and 
very  poisonous  substance,  soluble  in  water  and  alcohol. 
THEINE — An  alkaloid,  otherwise  known  as  caffeine (C8H10N4O2, 
H2O).    (See  Caffeine  and  Tea.) 


THEN  A  RDITE— THERMOMETERS  483 

THEN AEDITE— Natural  anhydrous  sodium  sulphate (Na2SO4). 

THEOBROMINE  (C7H8N4O2)— A  white,  crystalline,  poisonous 
drug  of  bitter  taste,  being  the  active  principle  of  cacao- 
beans,  and  nearly  allied  in  chemical  constitution  to  caffeine, 
which  can  be  produced  from  it  by  replacing  an  atom  of 
hydrogen  by  the  radical  methyl.  It  is  soluble  in  chloro- 
form, but  not  in  water  or  alcohol,  and  has  a  melting-point 
of  329°  C. 

THEORY — A  reasonable  systematic  view  of  ascertained  facts 
or  a  philosophical  explanation  of  known  phenomena — not 
so  conjectural  as  an  hypothesis. 

THERM — The  name  given  to  100,000  heat  units  by  Parliament 
as  the  new  basis  of  coal-gas  charges. 

"  THERM  ALINE  " — A  German  mixture  of  calcium  carbide 
and  crude  oil  in  sawdust,  which  upon  addition  of  water 
yields  a  mixture  of  fuel  gases,  consisting  of  acetylene  and 
the  vapour  generated  by  the  burning  crude  oil.  The 
mixed  gases  are  claimed  to  show  advantages  as  a  fuel  for 
high  temperatures. 

THERMAL  UNIT— See  Heat,  p.  244. 

"  THERMIT"  PROCESS— When  a  mixture  (thermit)  of  metal- 
lic aluminium  powder  and  ferric  oxide  is  subjected  to 
ignition  by  a  fuse  or  otherwise,  the  whole  mass  becomes 
incandescent,  the  aluminium  combining  with  the  oxygen  of 
the  iron  oxide,  and  setting  free  the  molten  iron,  which  forms 
a  layer  below.  The  temperature  realized  in  this  process  is 
estimated  at  about  3,500°  C.,  and  being  high  enough  to 
melt  all  known  metals,  the  process  is  utilized,  among  other 
applications,  for  the  repair  of  broken  castings  and  joining  up 
the  ends  of  tramway  rails  without  removal.  For  this  latter 
purpose,  a  mould  is  placed  round  the  rail-ends  in  such  wise 
as  to  receive  a  charge  of  the  molten  iron,  the  excess  metal 
being  afterwards  cut  away  or  otherwise  removed  as  required. 

THERMOLYSIS — A  term  sometimes  used  to  express  dissocia- 
tion of  chemical  compounds  under  the  influence  of  heat. 
(See  Dissociation.) 

THERMOMETERS— Instruments  used  to  ascertain  or  register 
temperatures  or  degrees  of  heat,  constructed  upon  the 
principle  of  the  expansion  of  fluids  by  heat.  Mercury 
is  the  fluid  usually  employed,  but  alcohol  is  used  for  low 
temperatures.  For  a  description  of  the  various  scales 
employed  see  Heat,  p.  241. 


484  THERMOSTAT— THORIUM 

THERMOSTAT — An  apparatus  designed  to  maintain  a  constant 
temperature. 

THINNERS— See  Paints. 

THIO-ACIDS  (Sulpho- Acids) — Compounds  analogous  to  oxy- 
acids  in  which  the  oxygen  is  replaced  by  sulphur. 

TfflOCYANIDES— See  Sulphocyanides. 

THIOLS— Mercaptans. 

THISTLE-FUNNEL — A  tube  with  small  funnel-head  by  means 
of  which  a  liquid  can  be  conveyed  into  any  vessel  with 
which  it  may  be  connected.  (See  p.  219.) 

THORIANITE —  A  heavy  black  mineral  containing  thoria 
mixed  with  uranium  oxides,  etc.,  found  in  Ceylon.  It 
usually  occurs  in  small  cubes,  has  a  sp.  gr.  of  9-5,  and  is 
amorphous  with  pitch-blende. 

THORITE — A  mineral  consisting  essentially  of  silicate  of 
thorium,  yellow  to  dark  brown  in  colour,  and  of  sp.  gr.  4*4 
to  5*4 ;  found  chiefly  in  Ceylon. 

THORIUM  (Th) — Atomic  weight,  232-5;  sp.  gr.,  about  n  ; 
melting-point  not  definitely  ascertained,  but  above  1,700°  C. 
It  is  a  rare  metal  occurring  in  the  minerals  thorite,  thorianite, 
orangcite,  and  monazite,  and  in  the  form  of  an  oxide  is  used 
in  the  preparation  of  mantles  for  use  with  incandescent 
gas  burners.  The  purer  thorium  compounds  are  worked 
up  from  the  raw  material  called  monazite  sand,  which  is 
essentially  a  phosphate  of  the  cerium  earths  and  occurs 
naturally  in  extensive  deposits  in  Carolina,  the  coast  of 
Brazil,  and  Travancore.  The  separated  monazite  from  the 
Travancore  deposits  contains  about  8J  per  cent,  of  thoria, 
as  compared  with  6  per  cent,  in  the  best  concentrates  from 
the  Brazilian  sands. 

Thorium  is  obtained  by  heating  the  double  chloride  of 
thorium  and  potassium  with  metallic  sodium,  and  as  thus 
produced  is  a  grey,  dense,  almost  infusible  powder. 

It  is  soluble  in  dilute  hydrochloric  and  sulphuric  acids, 
and  is  known  in  both  crystalline  and  amorphous  forms. 
Two  oxides  insoluble  in  water  (ThO2  and  Th2O7)  are 
known;  also  a  chloride  (ThCl4j,  and  a  white,  crystalline 
nitrate  (Th(NO3)4i2H2O),  both  of  which  are  soluble  in 
water;  also  other  compounds,  which  generally  resemble 
those  of  cerium. 

Meso-Thorium,  one  of  ten  radio-active  disintegration 
products  of  thorium;  exhibits  properties  similar  to  those 
of  radium.  It  is  a  regular  by-product  of  the  American 
manufacture  of  gas  mantles  from  monazite  sand,  and  is  said 


THORIUM-THYMOL  485 

THORIUM  (Continued)— 

to  be  specially  adapted  for  luminous  paint  in  respect  of 
articles  required  for  comparatively  short  periods.  (See 
also  Ionium.) 

THUJA  OIL— Distilled  from  the  leaves  of  the  white  cedar 
(Thuja  occidentalis),  containing  ^-pinene,  /-fenchone,  and 
thujone;  sp.  gr.,  0*915  to  0-925;  soluble  in  alcohol,  ether, 
etc.,  and  used  in  medicine. 

THUJONE — A  ketone  contained  in  thuja  oil  and  the  oils  of 
tansy  and  wormwood,  its  formula  being  variously  given  as 
C10H160  and  C10H18O. 

THULIUM  (Tm) — Atomic  weight,  168-5.  A  rare  element  of 
the  yttrium  group  identified  by  its  spectrum  and  found 
in  association  with  yttria  in  a  number  of  minerals,  in- 
cluding gadoliniUj  keilhanite,  euxenite,  and  samarskite. 

THYME  OIL— The  red  variety  of  thyme  oil  obtained  from 
garden  thyme  (Thymus  vulgaris  L.)  by  distillation  with 
water.  A  pound  of  thyme  yields  from  20  to  90  grains  of 
oil.  It  contains  the  phenolic  body  carvacrol  (C10H14O), 
which  is  isomeric  with  thymol,  but,  according  to  some 
statements,  no  thymol,  and  has  a  pleasant  odour  and 
camphoraceous  taste  ;  sp.  gr.,  0-9  to  0-95. 

It  is  stated  to  contain  usually  about  40  per  cent,  of 
phenols,  but  the  richest  oils  are  distilled  from  the 
Andalusian  Covydothymus  capitatus,  the  phenols  ranging 
from  55  to  upwards  of  67  per  cent. 

The  genuine  thyme  or  origanum  oil  is  stated  to  contain 
50  per  cent,  thymol  associated  with  a  terpene  named 
thymene  (C^H,.)  and  the  hydrocarbon  cymene  (C10H14). 
(See  Origanum  Oil  and  Thymol.) 

THYMOL  (C10H14O),  a  homologue  of  phenol,  is  a  white 
crystalline  substance  of  mild,  pleasant  odour  found  present 
in  origanum  oil,  also  in  the  volatile  oil  of  horsemint 
(monarda  oil)  and  in  oil  of  ajowan,  as  obtained  from  the 
fruit  of  the  herb  Ptychotis  ajowan,  which  is  grown  in  Persia, 
Egypt,  and  India.  It  is  but  slightly  soluble  in  water, 
dissolves  readily  in  alcohol  and  ether,  and  is  a  valuable 
antiseptic  and  preservative.  It  melts  at  49°  C.  Recent 
chemical  investigations  appear  to  indicate  that  the  best 
source  of  thymol  in  the  future  will  be  the  ketone  named 
piperitone,  which  is  contained  in  the  oil  yielded  by  the 
Eucalyptus  dives  and  from  which  it  can  be  made  by  a  re- 
duction process.  It  can  also  be  made  synthetically  from 
cymene. 


4&6  THYMOL—  Tltt 

THYMOL  (Continued)— 

The  percentages  of  thymol  in  various  essential  oils  have 
been  reported  as  follows  : 

Ajowan  oil            ...  ...  ...  40  to  50 

Thymus  vulgaris      ...  ...  ...  20  to  30 

Monarda  punctata   ...  ...  ...  60 

Carum  copticum       ...  ...  ...  45  to  55 

Ocimitm  viride         ...  ...  ...  37 

Origanum     hirtum     from  Crete     and 

Dalmatia            ...  ...  ...  60  to  67 

Moslajaponica        ..  ...  ...  44 

Wild  thyme  of  France  ...  ...  20 

"TIMONOX"  —  A  proprietary  brand  of  a  white  oxide  of 
antimony,  claimed  to  possess  the  essential  requirements  of 
a  first-class  pigment,  having  good  oil-absorption,  great 
opacity,  and  easily  ground  with  oil. 

TIN  (Stannum,  Sn)  and  its  Compounds  —  Atomic  weight,  118; 
sp.  gr.,  7'2  ;  melting-point,  232°  C.  Tin  is  found  in  nature 
for  the  most  part  in  the  form  of  oxide  (SnO2)  in  the  mineral 
known  as  tin-stone  (cassiterite)  in  Cornwall,  the  production 
in  1890  amounting  to  15,000  tons,  but  only  to  6,378  tons  in 
1918;  it  also  occurs  in  Malacca,  Bolivia,  Borneo,  and 
Mexico.  The  metal  is  prepared  from  it,  after  washing, 
by  a  process  of  calcination  with  anthracite  coal,  whereby 
the  oxygen  constituent  is  removed  in  the  form  of  carbon 
monoxide  and  the  metal  remains  behind  in  the  form  known 
as  block  tin  — 


Tin  is  a  bright  white  metal  which  can  be  obtained  in 
crystalline  form,  and  does  not  tarnish  in  the  air.  It  is  fairly 
soft,  ductile,  and  malleable. 

In  cold  dilute  nitric  acid  it  dissolves,  stannous  nitrate 
(4Sn(NO3)o)  being  formed,  while  the  corresponding  chloride 
is  formed  by  the  action  of  strong  hydrochloric  acid  upon 
the  metal. 

It  is  largely  used  in  the  process  of  tinning  iron  and  other 
metals,  ordinary  tin-plate  consisting,  for  example,  of  sheet- 
iron  coated  with  tin  on  the  surface  by  dipping  the  cleaned 
iron  plates  into  the  molten  tin.  It  has  valuable  applications 
by  reason  of  the  fact  that  it  is  not  acted  upon  by  many 
chemicals  which  readily  attack  iron  and  some  other  metals. 
It  enters  into  the  composition  of  many  alloys,  including 
solder,  brasses,  and  bronzes.  Britannia  metal  is  some- 
times made  of  84  parts  tin,  10  parts  antimony,  4  parts 


flN  AND  ITS  COMPOUNDS  4^7 

TIN  (Continued)— 

copper,  and  2  parts  bismuth,  whilst  pewter  consists  of  4  parts 
tin  and  i  part  lead. 

•  When  strongly  heated  in  the  air,  tin  takes  fire  and  forms 
stannic  oxide  (SnO2),  which  is  also  known  as  "putty 
powder  " — a  white,  insoluble,  amorphous  substance  which 
turns  yellow  on  heating,  and  is  not  acted  upon  by  acids  or 
alkalies.  It  is  used  as  a  polishing-powder  for  steel  and 
glass,  and  in  the  manufacture  of  certain  kinds  of  glass. 
The  lower  (stannous)  oxide  (SnO)  can  be  prepared 
by  heating  the  oxalate  out  of  contact  with  air,  or  in  a 
hydrated  form  (2SnOH2O)  by  adding  a  solution  of  sodium 
carbonate  to  one  of  stannous  chloride.  It  is  soluble  in 
acids,  forming  stannous  salts,  and  when  heated  in  the  air, 
it  becomes  peroxidized  to  SnO2.  The  hydroxide  dissolved 
in  sodium  hydrate  is  used  by  calico  printers  under  the  name 
of  "  sodium  stannite." 

Stannic  Acid  (SnH2O3)  is  obtained  in  hydrated  form  by 
adding  a  solution  of  calcium  carbonate  to  one  of  stannic 
chloride  in  insufficient  quantity  for  complete  precipitation, 
and,  as  thus  produced,  is  a  white  gelatinous  body  which 
forms  a  number  of  salts,  including  potassium  and  sodium 
stannates,  the  last  named  being  used  as  a  mordant  under 
the  name  of  "  tin  preparing  salt,"  and  made  by  fusing 
metastannic  acid  with  caustic  soda. 

Stannous  Chloride  (SnCl2),  a  white,  crystalline  body 
soluble  in  water,  obtained  by  dissolving  tin  in  hydro- 
chloric acid,  is  also  employed  as  so-called  "tin  salts"  by 
calico  printers  and  dyers  and  in  tin  galvanizing. 

Stannous  Chromate  (SnCrOJ,  an  insoluble  substance,  is 
used  in  decorating  porcelain. 

Stannous  Sulphate  (SnSO4),  a  heavy,  white,  crystalline 
powder,  soluble  in  water,  is  used  in  dyeing. 

Stannic  Chloride  (SnCl4)  is  obtained  by  the  action  of 
chlorine  gas  on  the  metal,  also  by  passing  chlorine  in  excess 
through  a  solution  of  stannous  chloride.  In  the  pure  an- 
hydrous state,  it  is  a  colourless  liquid  which  boils  at  120°  C., 
fumes  in  the  air,  and  forms  several  hydrates  with  water. 
One  of  these — viz.,  SnCl45H2O — is  crystalline,  soluble  in 
water,  and  is  also  used  as  a  mordant,  but  for  that  purpose  it 
is  more  usually  prepared  by  dissolving  tin  in  cold  aqua  regia, 
when  it  is  commercially  known  as  "oxymuriate  of  tin." 

Stannous  Sulphide  (SnS)  is  formed  when  tinfoil  is  intro- 
duced into  the  vapour  of  sulphur ;  the  metal  then  fires  and 
forms  the  leaden-coloured  stannous  sulphide. 


488  TIN— TIT  A  NI UM 

TIN  (Continued)— 

Stannic  Sulphide  (SnS2)  is  a  bright  yellow  crystalline 
powder  used  as  a  pigment  for  imitation  gilding  under 
the  name  of  "  mosaic  gold,"  and  is  obtained  as  the  resuty 
of  complicated  changes  by  heating  tin  amalgam  with 
sulphur  and  ammonium  chloride  in  a  retort.  It  is  soluble 
in  alkaline  sulphide  solutions  and  can  be  sublimed  to  some 
extent. 

When  a  solution  of  gold  chloride  is  added  to  a  dilute 
solution  of  stannous  chloride  a  splendid  purple  colour  is 
produced,  and  this  is  a  distinguishing  test  for  tin.  (See 
Purple  of  Cassius.) 

Stannic  Phosphide  (Sn2P2),  made  by  heating  the  metal 
together  with  phosphorus,  is  a  silver-white  compound,  used 
in  the  manufacture  of  phosphor-bronze. 

TINCAL— See  Boron. 

TINPLATE— See  Tin. 

TITANIUM  (Ti) — Atomic  weight,  48-1  ;  sp.  gr.,  4-5;  melting- 
point,  i, 800°  C.  Titanium  is  a  rare  element  occurring  in 
several  mineral  forms  (rutile,  brookite,  and  anastase),  and 
finds  some  employment  in  metallurgy.  It  is  obtained  as  a 
dark  grey,  amorphous  powder  by  heating  titanous  chloride 
with  metallic  sodium,  and  exhibits  a  tendency  to  combine 
directly  with  nitrogen,  forming  a  nitride.  It  is  soluble  in 
acids,  resembles  tin  in  many  of  its  properties,  and  forms 
two  oxides  (TiO  and  TiO2),  which  are  insoluble  in  water 
and  are  used  in  the  preparation  of  enamels  to  make  them 
more  resistant  to  corrosion. 

Titanous  Chloride  (TiCl3)  is  used  commercially  in  con- 
nection with  the  dyeing  of  cotton  goods,  when  over-dyeing 
has  occurred  and  require  "  stripping  "  before  re-dyeing. 

Titanium  Oxalate  (Ti2(C2O4)3.ioH2O)  is  a  yellow,  crys- 
talline salt,  soluble  in  water,  used  as  a  mordant  in  textile 
dyeing. 

Titanium  Sulphates  (Ti2(SO4)3  and  Ti2(SO4)29H2O)  are 
both  soluble  in  water  and  used  as  mordants. 

Titanium  Tetrachloride  (TiCl4),  a  colourless  liquid  of 
sp.  gr.  4*59,  soluble  in  water,  is  also  used  in  association 
with  potassium  bitartrate  as  a  mordant. 

Extensive  deposits  of  titanium  ore  are  found  in  the  New 
World,  Africa,  Australia,  Scandinavia,  and  in  the  Urals, 
and  the  growing  importance  of  titanium  dioxide  as  a 
pigment  has  led  to  a  process  being  worked  out  in  Norway 
for  the  production  of  this  compound  on  a  considerable 
scale  from  ilmenite  (titaniferous  iron  ore).  As  compared 


TITANIUM— TOPAZ  489 

TITANIUM  (Continued)— 

with  white-lead  and  zinc  oxide,  "titanium  white"  offers 
considerable  advantages,  possessing,  it  is  said,  a  greater 
covering  power,  being  non-poisonous,  chemically  inert, 
without  saponifying  action  upon  linseed  oil,  while  it  does 
not  blacken  upon  exposure. 

TITRATION— The  process  of  making  a  volumetric  deter- 
mination or  analysis  by  the  use  of  a  standard  solution. 
(See  Burette,  Reagents,  and  Volumetric  Analyses,) 

TOBACCO — The  leaf  of  the  Nicotiana  tabac^^mt  indigenous  in 
America,  and  extensively  cultivated  in  many  countries. 
Its  chief  active  principle  is  nicotine  (C10H14N2),  which  is 
present  to  the  extent  of  from  about  J  to  8  per  cent.,  and 
a  smaller  quantity  of  another  alkaloidal  poison  named 
nicotianine.  The  leaves  contain,  also,  a  large  amount  of 
extractives,  albuminous  bodies,  some  resin,  and  mineral 
salts  which  constitute  ihe  ash  left  upon  burning  (18  to 
23  per  cent.).  (See  Nicotine.) 

TOLU— See  Balsams. 

TOLUENE  or  METHYL  BENZENE  (Toluol)  (C7H8  or  C6H5CH3) 
— An  aromatic  hydrocarbon  of  sp.  gr.  0*8613,  being  a 
benzene  derivative  which  boils  at  110°  C.  and  is 
soluble  in  alcohol,  ether,  and  benzene.  It  finds  use  as 
a  solvent,  as  a  material  from  which  a  number  of  dyes  are 
manufactured,  and  in  the  preparation  of  "T.N.T."  explosive 
and  dyestuffs.  (See  Coal  and  Explosives.) 

TOLUIDINE  (C7H9N)  exists  in  three  isomeric  forms.  The 
solid  para  compound  is  a  white,  lustrous  substance  (con- 
tained in  commercial  aniline)  which  melts  at  43°  C.,  and  from 
which  many  red  and  violet  dyes  are  prepared.  The  ortho 
and  meta  compounds  are  liquids,  which  boil  at  about 
199°  C. 

TOLUOL  (Toluole)— A  commercial  form  of  toluene,  obtained 
from  the  distillation  of  coal  tar.  (See  Coal.)  It  is  also 
found  in  certain  natural  petroleums  and  can  be  produced 
by  "  cracking "  these  mineral  oils.  (See  Toluene  and 
Petroleum.) 

TONKA-BEANS  or  TO NQUIN- BEANS— The  fruit  of  Dipterix 
odorata  and  other  D.  species,  indigenous  in  Guiana,  con- 
taining coumarin  and  other  substances.  It  is  used  in 
perfumery. 

TOPAZ — A  silicated  aluminous  mineral  containing  fluorine  in 
combination,  occurring  in  gneiss  or  granite  (5(Al2O3.SiO2) 
+  Al2F6.SiF4).  The  best  crystals  come  from  Brazil,  and 
are  used  for  making  gems. 


490    TORRICELLIAN  VACUUM— TRIPHENYLMETHANE 

TORRICELLIAN  VACUUM— The  space  above  the  mercury  in  a 
barometer. 

TOURMALINE — The  name  given  to  a  group  of  rhombohedral 
double  silicates  of  colours  varying  according  to  their  com- 
position, and  usually  found  in  granite,  gneiss,  or  mica-slate. 
When  a  crystal  of  tourmaline  is  heated  to  about  150°  C.  it 
becomes  strongly  electrical. 

TOXIC — Poisonous ;  property  of  toxins.  (See  Toxalbumins  in 
Addenda.) 

TOXINS  or  TOXINES— Poisonous  substances  produced  in  dead 
bodies  and  putrid  animal  tissues.  (See  Ptomaines.) 

TRAGACANTH— See  Gums. 

TRANSLUCENT — Pellucid,  clear,  transparent. 

TRANSMUTATION— See  Elements  and  Radio-activity. 

TRANSPARENT — Admitting  the  passage  of  light ;  easily  seen 
through. 

TREACLE— See  Molasses. 

TRI  ACETINE  (C3H5(CH3CC>9)3— A  glyceride  prepared  by 
heating  glycerol  with  acetic  anhydride  in  presence  of 
finely  divided  hydrogen  potassium  sulphate.  It  is  used 
for  gelatinizing  and  lowering  the  freezing-point  of  nitro- 
glycerine. 

Its  sp.  gr.  is  1*1603  at  I5°  C.  ;  it  boils  at  258°  C.,  and 
is  miscible  with  alcohol,  ether,  chloroform,  and  benzine. 
It  is  a  narcotic  and  is  poisonous. 

TRICHLORACETIC  ACID  (CC13COOH)  —  A  deliquescent, 
colourless,  crystalline  compound  made  by  the  action  of 
chlorine  upon  glacial  acetic  acid  ;  used  in  medicine  and  for 
removing  corns  and  warts.  It  melts  at  573°  C.  and  boils 
at  195°  C. 

TRICHLORETHYLENE  (C2HC13)  is  a  liquid  which  boils  at 
88°  C.  and  is  used  for  the  extraction  of  oil-seeds  and  bones. 

TRIDYMITE — A  rare  mineral  form  of  crystalline  silica,  fre- 
quently occurring  in  volcanic  rocks. 

TRI-ETHYLAMNE— See  Amines. 

TRI-METHYLAMINE— See  Amines. 

TRI-NITRO-GLYCERINE— See  Explosives. 

TRI-NITRO-TOLUOL— See  Explosives. 

TRIONAL  or  METHYL  SULPHONAL  (CH3(C2H5)C(SO2C2H5)2 
=  C8H18S2O4) — A  crystalline  soporific  and  hypnotic,  soluble 
in  water,  alcohol,  and  ether ;  melting-point,  76°  C. 

TRIPHENYLMETHANE  (CH(C6H5)3)  is  a  colourless  crystal- 
line substance  which  melts  at  93°  C.,  boils  at  359°  C.,  and 


TRIPHENYLMETHANE-TUNG  OIL  491 

TRIPHENYLMETHANE  (Continued)— 

is  readily  soluble  in  hot  alcohol,  ether,  and  benzene.  Its 
derivatives  include  the  malachite  green,  rosaniline,  aurine, 
and  the  eosin  groups  of  dyes. 

TRIPHENYL  PHOSPHATE  ((C6H5)3PO4)— A  colourless  and 
somewhat*  deliquescent  crystalline  substance  used  as  a 
camphor  substitute  in  making  "  dope  "  and  impregnating 
roofing  paper,  etc.  It  melts  at  53°  C.,  boils  at  245°  C., 
and  is  soluble  in  alcohol,  acetone,  ether,  and  benzene. 

TRIPOLI — An  impalpable  siliceous  earth  resulting  from  the 
natural  decomposition  of  chert  or  siliceous  limestone,  and 
used  as  an  abrasive  and  polishing-powder.  When  pure  it 
is  white,  and  most  of  the  grains  are  less  than  0*01  mm.  in 
diameter. 

TRIPOLITE— See  Kieselguhr. 

TRITURATION— Grinding  to  a  very  fine  powder. 

TRONA — Natural  deposits  of  sodium  sesquicarbonate  mixed 
with  potassium  and  boron  salts  occurring  in  Egypt,  Africa, 
the  United  States,  and  South  America. 

TRYPSIN — An  enzyme  contained  in  the  pancreas,  capable  of 
changing  albuminous  matters  into  so-called  albumoses,  in 
which  partially  hydrolysed  and  more  soluble  state  they  be- 
come converted  into  peptone.  (See  Enzymes  and  Peptones.) 

TUNA  OIL— See  Fish  Oils. 

TUNG  OIL  (Chinese  Wood  Oil,  Hankow  Wood  Oil)  is  ob- 
tained by  pressure  from  the  seeds  of  Aleurites  cordata  and 
A .  fordii,  indigenous  in  China  and  Japan.  It  is  also  ex- 
pressed in  Madagascar  and  known  there  as  bakoby  oil. 
It  is  yellow  in  colour,  of  drying  character,  composed  of 
glycerides,  of  unpleasant  odour,  and  liable  to  solidify 
when  kept.  Its  sp.  gr.  is  0-9360  to  0-943  J  saponifica- 
tion  value,  190  to  195 ;  iodine  value,  150  to  165 ;  and 
refractive  index,  1*503.  It  comes  to  the  market  in  various 
grades  of  colour — colourless,  black,  yellow,  etc. — and  is 
used  as  a  water- proofing  material  for  paper,  and  in  making 
varnishes,  driers,  and  linoleum.  It  contains  a  proportion 
of  free  fatty  acids,  varying  from  2  to  4-6  per  cent.,  but  for 
varnish- making  it  should  be  prepared  so  that  this  content 
does  not  exceed  i  per  cent. 

It  is  frequently  adulterated  with  cotton-seed  and  soya-bean 
oils,  etc.  When  heated  to  250°  C.  for  a  short  time  it  forms 
a  jelly,  due  to  polymerization,  a  characteristic  not  so 
strongly  exhibited  by  any  other  glyceride. 

In  China  and  Japan  it  is  used  for  varnishing  wood  and 
caulking  boats. 


492  TUNGSTEN 

TUNGSTEN  (Wolfram)  (W) — Atomic  weight,  184;  sp.  gr., 
1877;  melting-point  about  3,267°  to  3,350°  C. ;  a  hard, 
grey,  heavy,  ductile  metal  of  great  tensile  strength,  highly 
prized  for  use  in  hardening  and  toughening  steel  as  specially 
made  for  high-speed  metal-cutting  tools  and  for  making  the 
filaments  of  incandescent  electric  lamps.  Ror  this  latter 
application,  the  powdered  metal  is  fused  or  sintered  together 
by  the  passage  of  an  electric  current,  the  tensile  strength 
of  the  finished  wire  of  o'oon  inch  diameter  being  given  as 
270  tons  per  square  inch. 

It  occurs  in  nature  as  wolfram  (wolframite)  and  scheelite, 
the  former  term  being  often  used  to  cover  all  minerals  in 
which  tungsten  tri-oxide  is  combined  with  the  protoxides 
of  iron  and  manganese.  They  vary  widely  in  proportion, 
and  are  found  chiefly  in  proximity  to,  or  mixed  with,  tin  ores. 
Wolframite  is  heavy,  black,  and  of  great  specific  gravity  (7'o), 
so  that  it  can  be  easily  concentrated  from  the  associated 
gangue,  but  not  so  easily  from  tin  oxide  (cassiterite) -}  as,  how- 
ever, it  is  feebly  magnetic,  while  the  cassiterite  is  not,  this 
property  can  be  used  to  effect  separation  when  associated. 

Deposits  are  found  in  China,  Japan,  Chili,  Peru,  and 
Argentine,  the  Chinese  deposits  (in  the  Kwangsi  and  Qwan- 
tung  Provinces)  being  reported  as  large.  A  small  sample 
of  ore  from  the  Waichow  district  recently  analyzed,  was 
found  to  contain  55*84  per  cent,  tungsten,  13*25  per  cent, 
iron,  and  11*56  per  cent,  manganese. 

Scheelite,  or  calcium  tungstate  (CaWO4),  is  a  heavy 
yellowish  or  brown-purple  mineral,  of  wax-like  appearance, 
and  the  supply  is  small  as  compared  with  wolframite.  It 
is  chiefly  used  in  the  manufacture  of  ferro-tungsten,  on 
account  of  the  practical  difficulties  experienced  in  isolating 
the  oxide  in  order  to  prepare  the  pure  metallic  tungsten. 
Supplies  come  from  the  United  States,  Bolivia,  Portugal, 
Burma,  Malaya,  Australia,  New  Zealand,  and  Cornwall. 

Above  one-half  of  the  natural  supplies  of  tungsten  ores 
is  mined  in  the  British  Empire,  a  large  proportion  of  the 
302  tons  of  metal  produced  in  1918  having  been  obtained 
from  tin  mines,  and  95  per  cent,  of  the  total  ores  was 
used  in  the  production  of  high-speed  tool  and  other  alloy 
steels  containing  tungsten  in  proportions  varying  from  2  to 
20  per  cent,  according  to  the  application. 

The  direct  reduction  of  the  ores — which  yields  ferro- 
tungsten  suitable  for  most  purposes — is  effected  by  mixing 
the  ore  concentrates  with  anthracite  and  roasting  in  an  open 
furnace,  i  ton  of  98^5  per  cent,  metal  being  yielded  by  2  tons 
of  the  purer  concentrates.  To  prepare  the  metallic  powder 


TUNGSTEN— TURMERIC  PAPER  493 

TUNGSTEN  (Continued) — 

the  tungstic  oxide  (WO3)  has  to  be  isolated  from  associated 
matters,  and  this  can  only  be  done  by  chemical  processes 
involving  the  application  of  mineral  acids  or  fusion  with 
alkali,  both  methods  being  employed  in  practice.  The 
acid  attack  is  designed  to  dissolve  out  the  iron,  manganese, 
and  other  oxides,  leaving  the  WO3  as  an  insoluble  residue ; 
whereas,  by  furnacing  with  soda  ash,  tungstate  of  sodium 
is  produced,  and  from  this  the  WO3  can  be  precipitated 
by  the  addition  of  dilute  acid. 

Tungstic  oxide  (WO3)  is  a  well-defined  compound,  and 
yields  a  salt  corresponding  to  potassium  dichromate. 

Metallic  tungsten  can  be  obtained  by  the  alumino-thermic 
reduction  of  tungstic  oxide. 

Both  tungstic  oxide  and  sodium  tungstate  are  in  demand 
for  various  minor  industries. 

Tungstic  acid  (W2O5(OH)2)isa  yellow  powder,  insoluble 
in  water,  which  can  be  obtained  in  a  crystalline  condition, 
and  finds  use  as  a  mordant ;  while  sodium  tungstate 
(NagWO^HgO)  a  colourless  crystalline  body,  made  as 
already  described,  is  soluble  in  water,  and  used  for  fire 
proofing  fabrics  and  in  the  preparation  of  other  tungsten 
compounds. 

Calcium  tungstate  is  used  in  connection  with  plates  for 
radiography  for  translating  X  rays  into  rays  of  far  greater 
wave-lengths  of  increased  actinic  power. 

TURACINE — A  nitrogenous,  organic,  red  colouring  matter  con- 
tained in  the  feathers  of  the  African  birds  named  turacos, 
containing  8  per  cent,  of  copper  which  is  doubtless  obtained 
from  the  local  soil,  as  it  is  known  to  contain  malachite. 
Apart  from  the  copper  constituent,  the  colouring  matter 
would  appear  to  have  much  the  same  composition  as  the 
colouring  matter  of  blood. 

TURKEY  RED— See  Madder. 

TURKEY  RED  OIL— Sulphonated  castor  oil  used  in  the  textile 
and  leather  industries. 

TURMERIC — A  yellow  or  saffron  colouring  matter  prepared 
from  the  roots  of  an  East  Indian  plant  (Curcuma) ;  used  for 
dyeing,  also  in  pharmacy  and  medicine,  and  as  a  constituent 
of  curry  powder. 

TURMERIC  PAPER — Absorbent  paper  coloured  with  a  solution 
of  the  yellow  colouring  matter  of  turmeric,  which  is  turned 
brown  by  alkaline  solutions,  and  is  sometimes  used  in 
place  of  litmus  paper.  (See  Litmus.) 


494  TURNBULL'S  BLUE— TURPENTINE 


TURPENTINE — Oil  or  spirits  of  turpentine  is  a  mixture  of 
the  hydrocarbons,  known  as  terpenes,  produced  by  nature  in 
pine-trees,  but  spruce  turpentine  is  said  to  consist  largely  of 
cymene.  The  oil  is  collected  by  making  cuts  or  slits  in 
the  bark  of  the  trees,  through  which  there  exudes  gum 
thus,  or  "  crude  turpentine,"  and,  when  this  is  distilled 
with  steam,  the  oil  or  spirit  of  turpentine  passes  over  as 
vapour  and  is  afterwards  condensed,  leaving  rosin  behind. 

There  are  many  kinds  of  turpentine,  meaning  the  crude 
products  as  they  exude  from  the  trees,  and  as  many  cor- 
responding oils  or  spirits  of  turpentine. 

American  turpentine  is  obtained  chiefly  from  Pinus 
australis  and  Pinus  tcsda ;  French  turpentine  from  Pinus 
maritima  and  Pinus  pinaster ;  Russian  turpentine  from  Pinus 
sylvestris  and  Pinus  ledebourii ;  German  turpentine  from  the 
Scotch  fir  Pinus  sylvestvis  and  Abies  pectinata,  etc.;  Strasburg 
turpentine  from  the  silver  fir,  A  bies  pectinata ;  Venice  tur- 
pentine from  the  larch,  Larix  Euvopcea ;  Indian  turpentine 
from  Pinus  longifolia  Roxb. ;  Burma  turpentine  from 
Pinus  Khassyia  (corresponding  to  the  American  product); 
and  Chio  turpentine  from  Pistacia  terebinthus  and  Pinus  vera. 

"  Pine-cone  oil "  is  obtained  by  distilling  the  cones  of 
Abies  pectinata  with  water,  and  "pine-leaf  oil"  similarly 
from  the  leaves  of  Pinus  sylvestris  or  Pinus  abies.  There  are 
also  varieties  of  "pine-needle  oils"  prepared  from' the  needles 
of  the  various  species  of  pines. 

The  crude  turpentine  which  concretes  upon  the  bark  of 
the  trees  tapped  for  turpentine  in  France  is  variously  called 
galipot  and  barras,  and  is,  for  the  most  part,  rosin. 

The  turpentines  find  uses  in  the  crude  forms  in  which 
they  exude  from  the  trees  which  produce  them,  but  for  the 
most  part  the  oil  or  spirit  is  first  of  all  distilled  from  the 
crude  materials  and  are  then  utilized  as  solvents  and  as 
volatile  vehicles  in  connection  with  many  manufactured 
articles,  including  paints,  varnishes,  disinfectants,  etc.,  also 
in  pharmacy  and  medicine. 

Turpentine  oils,  irrespective  of  source,  are  colourless 
mobile  fluids  each  of  more  or  less  characteristic  odour 
insoluble  in  water,  but  soluble  in  alcohol,  ether,  and  carbon 
disulphide,  and  miscible  with  many  other  organic  fluids. 
They  vary  in  specific  gravity  from  0^865  to  o'875,  boiling- 
points  from  160°  to  162°  C.,  and  optical  rotatory  power,  and 
they  differ  not  only  in  respect  of  their  origin,  but  to  some 


T UR  PENTINE— ULTRA  MA  RINE  495 

TURPENTINE  (Continued) — 

extent  even  among  themselves  so  far  as  they  come  from 
a  common  source. 

Turpentine  absorbs  oxygen  when  exposed  to  the  air, 
oxygen,  or  ozone,  and  produces  a  body  of  the  character 
of  a  peroxide,  which  in  presence  of  water  gives  rise  to  the 
formation  of  hydrogen  dioxide,  and  this  property  is  utilized 
in  the  manufacture  of  "  Sanitas  fluid,"  the  well-known 
disinfectant.  This  absorptive  capacity  for  oxygen  is  more 
pronounced  in  the  Indian,  Russian,  and  other  sylvestre 
classes  of  turpentine.  (See  also  Essential  Oils,  Balsams, 
Terpenes,  and  Rosin.) 

TURPETH — A  mineral  basic  mercuric  sulphate  (Hg3SO6  or 
HgS04,2HgO). 

TURQUOISE — A  gem  consisting  of  hydrated  aluminium  phos- 
phate coloured  by  copper  and  iron. 

TWITCHELL  PROCESS— See  Fats. 

TYPE-METAL— See  Antimony. 

TYRIAN  PURPLE — A  purple  dye  chemically  associated  with 
indigo,  extracted  from  a  species  of  murex,  a  mollusc  found 
in  the  Mediterranean. 

TYROSINE  (CgH^NOg) — A  crystalline  body  of  silk-like  lustre 
sparingly  soluble  in  cold  water,  alcohol,  and  ether,  but 
soluble  in  boiling  water.  It  is  of  amino-acid  character  and 
is  found  present  in  the  pancreatic  gland,  in  old  cheese,  and 
as  a  product  of  putrefactive  decomposition  of  some  albu- 
minous substances,  as  also  of  their  chemical  hydrolysis. 
It  forms  a  definite  additive  crystalline  hydrochloride 
(C9HUNO3,HC1)  with  hydrochloric  acid,  and  is  one  of  the 
organic  substances  that  have  been  built  up  synthetically. 

U-TUBES— See  Drying  Tubes. 

ULEXITE— See  Boron. 

ULTRAMARINE — A  valuable  blue  pigment  of  complicated 
composition  containing  aluminium  in  the  form  of  silicate 
found  in  Persia  and  Turkestan  and  known  as  lapis  lazuli. 
It  is  now  made  artificially  by  exposing  to  a  red  heat,  but 
below  fusing-point  (750°  to  800°  C.),  a  mixture  of  kaolin  or 
powdered  quartz  of  high  purity,  sodium  carbonate  or  caustic 
soda,  sulphur,  and  charcoal  (or  pitch  or  tar),  supplemented 
by  some  subsequent  treatment.  Its  exact  constitution  is 
not  known,  and  it  can  be  made  of  various  tints,  green 
included.  Its  essential  formula  has  been  given  as 
Na4(NaS3.Al)Al2(SiO4)3.  Another  description  gives  the 
poor  in  silica  anid  rich  in  sulphur  blue  type  as  represented 


496  ULTRA  MA  RINE—  URA  NI UM 

ULTRAMARINE  (Continued)— 

by  the  formula  Na8Al6SigS4O24,  and  the  rich  in  silica  and 
poor  in  sulphur  type  as  Na6Al4Si6S4O20.  One  mixture  used 
for  producing  a  bright  blue  product  consists  of  540  kilos 
kaolin,  8  kilos  caustic  soda,  538  kilos  soda  ash,  268  kilos 
sulphur,  and  46  kilos  charcoal.  It  is  used  in  making 
laundry  blues,  paints,  colours,  and  paper-manufacture. 

ULTRA-MICROSCOPE— A  microscope  so  constructed  that  by 
the  aid  of  very  intense  and  localized  light,  the  intensity  of 
reflection  of  the  substance  under  examination  is  greatly 
increased,  thus  correspondingly  increasing  the  power  of 
vision. 

UMBER  (Sienna) — A  pigment  used  in  paint-making,  consisting 
of  a  natural  oxide  of  iron  allied  to  ochre  ;  another  variety 
is  in  the  nature  of  a  brown  haematite  of  the  composition 
2Fe2O3,SiO2,H2O.  The  deposits  vary  in  colour^  (from 
yellow  to  brown)  and  in  composition. 

UNSATURATED  COMPOUNDS  possess  unsatisfied  affinities, 
such  as  phosphine  (PH3),  in  which  three  only  out  of  the 
five  affinities  are  saturated  by  combination  with  hydrogen, 
leaving  two  unsatisfied;  again,  ethylene  (C2H4),  which 
may  be  regarded  as  only  a  half-saturated  compound.  On 
the  other  hand,  phosphorus  pentoxide  is  a  saturated 
compound.  (See  Saturated  Compounds  and  Valencies.) 

UPAS — Arrow  poison  used  in  the  East  Indies,  obtained  from 
the  milky  juice  of  the  Upas  ant  jar  and  Upas  radja. 

URALITE — Hornblende  from  the  Ural  districts. 

URANINE  (NajjC^H^Og)  -A  yellow,  crystalline  dye,  obtained 
by  treating  fluorescein  with  sodium  carbonate ;  used  also 
for  following  the  course  of  subterranean  waters,  etc. 

URANINITE— Pitch-blende. 

URANITE — Uranium  minerals,  one  of  which  is  a  phosphate  of 
uranium  and  copper,  and  the  other  a  phosphate  of  uranium 
and  calcium. 

URANIUM  (U)— Atomic  weight,  238-2  ;  sp.  gr.,  18-68.  This 
metal  in  the  form  of  an  oxide  (UO2,2UO3)  is  contained  to 
the  extent  of  from  40  to  90  per  cent,  in  the  mineral  pitch- 
blende which  is  found  in  some  Cornish  mines.  It  also 
occurs  in  uranite,  and  in  a  number  of  other  minerals  in 
association  with  other  substances,  including  carnotite,  fev- 
gusonite,  samarskite,  etc.  It  is  silver-white  in  appearance, 
heavy,  melts  at  a  bright  red  heat  (about  800°  C.),  is  soluble 
in  acids,  and  is  made  by  reduction  of  the  oxides  with 
carbon  in  the  electric  furnace. 


URANIUM— URINE  497 

URANIUM  (Continued)— 

There  are  an  indefinite  number  of  oxides  (which  are  in- 
soluble in  water),  the  best  known  being  represented  by  the 
formula  UO2,  UO3,  and  UO4,  used  in  the  ceramic  indus- 
tries, and  amongst  the  other  better  known  salts,  are  uranous 
sulphate  (U(SO4)2),  chlorides  (UC13,  UC14,  and  UC15),  and 
the  nitrate  (UO2(NO3)2).  The  uranous  salts  are  green 
and  the  uranic  ones  yellow  in  colour,  most  of  which  are 
soluble  in  water. 

Some  uranium  compounds  are  employed  to  give  a  yellow 
fluorescent  colouration  to  glass,  whilst  the  lower  oxide  gives 
a  fine  black  colour. 

As  an  element,  uranium  is  the  more  interesting,  as  there 
are  reasons  for  supposing  that  by  some  sort  of  molecular 
disintegration  it  gives  rise  to  the  production  of  not  only 
radium  and  helium,  but  also  some  peculiar  radium  emana- 
tions (distinct  in  some  respects  from  radium),  and  a 
peculiar  form  of  lead.  The  radio-active  constituent  of 
uranium  salts  is  precipitated  from  solution  by  ammonia, 
but  in  course  of  time  the  radio-activity  is  recovered.  (See 
Radium  and  Lead.) 

UREA  or  CARBAMIDE  (CH4N2O)— A  white,  crystalline  sub- 
stance known  as  a  constituent  of  urine,  resulting  from 
oxidation  of  certain  nitrogenous  bodies  in  the  animal 
organism.  An  adult  man  excretes  about  30  grms.  daily.  It 
is  soluble  in  water  and  alcohol  and  is  one  of  the  organic 
bodies  that  has  been  built  up  synthetically  from  inorganic 
materials.  Ammonium  cyanate  is  easily  transformed  into 
urea  (with  which  it  is  isomeric),  and  urea  can  also  be 
made  by  the  action  of  ammonia  on  ethyl  carbonate  and 
by  the  action  of  mercuric  oxide  on  oxamide.  It  melts  at 
132°  C.  and  forms  compounds  with  acids  and  with  bases. 
(See  Cyanic  Acid.) 

URIC  ACID  (C5H4N4O3)— A  white  crystalline  constituent  of 
urine  forming  the  principal  part  of  urinary  calculi  and 
deposits,  very  slightly  soluble  in  water. 

It  is  also  found  in  the  urine  of  birds  and  serpents,  and 
gives  rise  to  a  number  of  derivates,  including  alloxan 
(C4H2N2O4),  which  may  be  viewed  as  amides  containing 
the  radical  C2O2  of  oxalic  acid. 

URINE — An  excretory  liquid  containing  the  soluble  broken-up 
or  waste  products  of  the  living  organism.  It  has  an 
average  sp.  gr.  of  1-02,  and  amounts  to  from  1,400  to 
i, 600  c.c.  per  twenty-four  hours,  containing  dissolved 

32 


498  URINE— VALENCIES 

URINE  (Continued)— 

solid  matters  to  the  extent  of  from  50  to  60  grms.,  including 
urea,  uric  acid,  kreatine,  kreatinine,  smaller  amounts  of 
undetermined  and  varying  constituents,  and  a  number  of 
mineral  salts. 

.  Kryptophanic  Acid  (C6H9NO6)  is  the  normal  free  acid 
of  human  urine,  although  it  has  been  stated  that  hippuric 
acid,  which  is  a  normal  constituent  of  the  urine  of  herbi- 
vorous animals,  is  sometimes,  if  not  always,  present  in  small 
quantity  in  the  human  liquid  excretion. 

VACUUM — A  space  de voided  of  air  or  gas  as  far  as  practicable, 
as,  for  example,  the  exhausted  glass  lamps  used  for  electric 
lighting.  The  Thermos  flask  has  a  practically  vacuous 
annular  space  between  the  two  glass  vessels  of  which  it  is 
constructed.  (See  Pumps.) 

VALENCIES — The  atoms  of  elements  possess  a  power  of  com- 
bination, or  so-called  valency,  more  or  less  peculiar  in  char- 
acter. Hydrogen  is  a  so-called  ww^valent  element — that 
is,  it  has  only  one  capability  of  chemical  attachment  to 
another  element.  Thus,  it  may  be  made  to  combine  with 
chlorine,  and  the  combination  may  be  graphically  repre- 
sented as  follows : 

- — -  /^^ 

Cl 


Hydrogen,  then,  and  the  other  elements  which  have  a 
similarly  restricted  valency  are  called  monads. 

Oxygen,  on  the  other  hand,  generally  behaves  as  a 
^'valent  element,  and  can  combine,  for  example,  with 
2  atoms  of  hydrogen  or  other  monovalent  element,  as 
shown  by  the  constitutional  formula  of  water,  H2O,  which 
may  be  graphically  expressed  thus : 


0 0 _0 


In  other  combinations,  oxygen  behaves  as  a  tetrad — as, 
for  example,  when  it  exists  in  combination  with  hydrogen 
as  hydrogen  dioxide  (H2O2). 


VALENCIES 


499 


VALENCIES  (Continued)— 

This  represents  the  view  that  i  atom  of  oxygen  is  at- 
tached, on  the  one  hand,  directly  to  the  2  atoms  of  hydro- 
gen, and  (as  there  is  reason  for  thinking)  the  other  atom  of 
oxygen  is  itself  not  in  direct  attachment  or  combination 
with  the  hydrogen  atoms. 

Nitrogen  is  an  example  of  a  tfn'valent  element,  although 
in  some  compounds  it  behaves  as  a  pentad  or  pentavalent. 
For  example,  in  ammonia  (NH3)  it  exists  in  combination 
with  3  atoms  of  hydrogen,  and  may  be  represented  as 
follows : 


whereas,  combined  as  in  chloride  of  ammonium  (NH4C1), 
it  would  appear  to  exist  in  pentavalent  combination,  thus : 


Carbon  is  an  example  of  the  tetrad  class — that  is  to  say, 
it  has  the  power  of  combining  with  4  atoms  of  hydrogen 
or  2  atoms  of  oxygen,  as  expressed  in  the  two  following 
graphic  formulae : 


(Methane  or  marsh  gas)  (Carbon  dioxide) 

(See  Saturated  and  Unsaturated  Compounds.) 


500  VALERIAN— VANADIUM 

VALERIAN — The  dried  rhizome  and  roots  of  Vakriana 
officinalis  containing  starch,  a  resinous  substance,  the 
essential  oil  of  valerian,  and  other  substances ;  100  parts 
of  the  root  yield  from  about  J  to  ij  parts  of  the  oil,  which 
can  be  obtained  by  distillation  with  water.  The  oil  has  a 
sp.  gr.  of  0*94  to  0-95,  and  is  soluble  in  alcohol  and  ether. 
It  is  of  complicated  composition  ;  yellow-greenish  in  colour  ; 
has  a  characteristic  strong  odour  and  aromatic  taste,  and 
contains  some  proportion  of  a  terpene  (C10H16),  also  some 
valeric  acid  (C5H10O2).  The  medicinal  (carminative)  action 
of  the  root  is  really  that  of  the  oil. 

The  Japanese  valerian  oil  is  known  as  kesso  oil,  and  has 
a  sp.  gr.  of  0-996.  All  the  varieties  are  soluble  in  alcohol 
and  ether. 

VALERIC  (VALERIANIC)  ACID  (C5H10O2)— An  acid  of  the 
fatty  series  which  bears  the  same  relation  to  amyl  alcohol 
as  acetic  acid  to  ethyl  alcohol.  It  is  said  to  exist  in  four 
different  modifications,  the  normal  variety  being  a  liquid 
which  boils  at  185°  C.,  and  is  soluble  in  alcohol  and  ether. 
One  of  the  varieties  is  found  naturally  in  many  plants, 
particularly  valerian  root  (see  Valerian)  and  in  angelica 
root  from  which  it  is  obtained  by  boiling  with  soda. 

Valeric  acid  is  a  frequent  product  of  the  oxidation  of  the 
higher  fatty  acids,  and  can  be  prepared  by  the  oxidation 
of  amyl  alcohol.  It  is  used  in  medicine  and  perfumery. 

VALONIA — Acorn  cups  of  the  Quercus  ^gilops,  Q.  vobuv)  and 
Q.  suber^  rich  in  tannin  ;  grown  in^  Turkey,  Greece,  and 
Roumelia,  and  used  for  tanning. 

VANADITE— See  Vanadium. 

VANADIUM  (V) — Atomic  weight,  51*2;  sp.  gr.,  6-025  ;  melt- 
ing-point about  1,730°  C.  Vanadium  is  a  somewhat  rare 
metallic  element  which  occurs  naturally  in  some  minerals, 
including  vanadite  (a  lead  combination),  pucherite  (a  bismuth 
combination),  mottvamite  (a  lead  and  copper  combination), 
and  patroniU  (an  impure  vanadium  sulphide  mined  in 
Peru). 

Vanadium  has  a  commercial  importance  in  connection 
with  the  manufacture  of  certain  kinds  of  steel,  to  which 
a  very  small  proportion — little  more  than  \  per  cent. — 
contributes  tensile  strength  and  certain  other  special 
properties  of  much  value  for  some  particular  applications. 

It  is  found  present  in  Bessemer  slag  at  times,  being 
derived  from  certain  iron  ores  in  which  it  occurs  natur- 
ally in  small  amount.  The  metal  is  soluble  in  strong 
acids,  and  when  heated  in  air  burns  brilliantly,  forming  the 


VANADIUM— VAPOUR  DENSITIES  501 

VANADIUM  (Continued)— 

pentoxide  (V2O5).  It  is  said  to  form  five  oxides  corre- 
sponding to  the  oxides  of  nitrogen ;  it  also  forms  a  nitride 
with  nitrogen,  three  chlorides  (VC12,  VC13,  and  VC14)  and 
acts  as  a  feeble  base. 

The  tetrachloride,  which  is  dark  green  and  soluble  in 
water,  is  used  as  a  mordant  in  the  textile  industry ;  the 
oxides  are  insoluble  in  water  and  are  used  in  metallurgy ; 
and  two  sulphates  (green  and  blue  salts,  soluble  in  water) 
are  also  used  as  mordants. 

VANILLA — The  pods  of  Vanilla  planifolia,  an  orchid  which 
grows  wild  in  Mexico,  Brazil,  and  Guiana,  and  is  cultivated 
in  many  tropical  countries,  contain  shining  crystals  of 
vanillin  (C8H8O3)  in  association  with  other  constituents, 
and  have  a  pleasant  aromatic  taste  and  odour. 

Vanilla  is  used  largely  for  flavouring  purposes  and  in 
medicine.  The  odoriferous  principle  (vanillin)  is  prepared 
on  a  large  scale  from  coniferin  (C16H22O8  +  2H2O),  a  com- 
pound present  in  the  sap  of  the  cambium  in  the  conifers. 
This  by  hydrolysis  yields  glucose  and  coniferyl  alcohol, 
and  the  latter  by  oxidation  gives  vanillin.  It  can  also  be 
obtained  by  the  oxidation  of  eugenol,  ozone  being  one  of 
the  agents  employed.  Vanillin  is  soluble  in  water,  alcohol, 
and  ether,  and  melts  at  80°  C. 

VAPOUR  DENSITIES — The  relative  weights  of  gases  at  the 
same  temperature  and  pressure  compared  with  hydrogen 
as  the  unit,  determined  either  by  ascertaining  the  weight 
of  a  given  volume  or  the  volume  of  a  given  weight  of  vapour. 
These  densities  or  specific  gravities  of  the  elements  are  in 
some  cases  identical  with  their  atomic  weights,  including 
hydrogen,  oxygen,  nitrogen,  chlorine,  bromine,  iodine, 
sulphur  and  selenium.  The  exceptions  to  the  rule  include 
mercury,  cadmium,  zinc,  potassium,  sodium,  arsenic  and 
phosphorus,  the  first  five  named  of  which  have  densities  one- 
half  of  their  atomic  weights,  and  the  last  two  twice  that 
of  their  atomic  weights. 

The  general  law  is  that  the  vapour  densities  of  the 
elements  are  one-half  of  their  molecular  weights,  and  the 
explanation  of  the  noted  exceptions  lies  in  the  fact  that 
the  molecules  of  mercury,  cadmium,  zinc,  potassium  and 
sodium,  consist  of  but  one  atom,  so  that  their  atomic  and 
molecular  weights  are  identical,  while  arsenic  and  phos- 
phorus contain  each  four  atoms  in  their  molecules,  and 
their  smallest  part  that  can  take  part  in  a  chemical  change 
is  one-fourth  of  their  molecular  weights  or  one-half  of  their 
densities.  (See  Gases,  Molecules,  and  Valencies.) 


502  VAREC—  VEGETABLE  OIL  SEEDS 

VAREC — The  Normandy  name  for  the  ashes  of  seaweeds, 
(See  Barilla  and  Vriac.) 

VARNISHES  are  solutions  of  resinous  substances  which,  when 
spread  over  the  surface  of  any  object,  leave  behind,  after 
evaporation  of  the  volatile  vehicle,  a  thin  shiny  layer  of 
the  dissolved  bodies.  Varnishes  are  used  as  protective 
coverings  to  painted  wooden,  iron,  and  other  surfaces. 
Copal,  shellac,  dammar,  sandarach,  mastic,  elimi,  benzoin, 
anime,  resin,  asphalt,  etc.,  are  all  used  in  compounding 
them  according  to  the  purpose  of  their  applications,  copal 
varnish  being  one  of  the  most  important.  To  dissolve 
copal  and  some  of  the  other  gums,  it  is  requisite  to  powder 
and  subject  them  to  a  process  of  dry  distillation  at  a 
temperature  of  about  360°  C.,  by  which  treatment  they  lose 
from  20  to  25  per  cent,  of  their  weight.  They  can  then 
be  dissolved  in  turpentine  and  boiled  linseed  oil.  While 
these  two  liquids  are  used  in  compounding  ordinary  varnishes, 
others  are  made  using  spirits  of  wine,  or  petrol,  or  turpen- 
tine, or  other  solvent  alone. 

Driers  are  chemical  materials  used  in  varnish  and  paint 
making  to  facilitate  the  drying  process.  For  varnish-making, 
manganese  dioxide,  manganese  resinate,  manganese  borate, 
and  litharge  (lead  oxide)  are  used ;  while  for  paints,  apart 
from  the  drying  properties  of  any  lead  oxides  that  may  be 
incorporated,  and  that  of  the  varnish  itself  (when  incorpor- 
ated in  the  paints),  the  drying  depends  mainly  upon  the 
boiled  linseed  oil  used  in  compounding  them.  (See  Ester 
Gums  and  Paints.) 

VASELINE — A  solid,  jelly-like  substance  composed  almost 
entirely  of  highly  saturated  hydrocarbons,  obtained  as  a 
residual  from  the  distillation  of  petroleum,  and  subse- 
quently purified  from  associated  bodies.  It  is  used  in 
compounding  ointments,  in  preparation  of  polishes,  as  a 
lubricant,  and  in  leather-dressing,  etc.  (See  Petroleum.) 

VEGETABLE  BLACKS — Carbon  from  various  sources  used  as 
pigments.  (See  Bone  Black,  Ivory  Black,  and  Lamp 
Black.) 

VEGETABLE  IVORY — The  tagua-nut  of  the  Phytelephas  macro- 
carpa  tree  which  grows  in  Columbia  (South  America).  It 
has  the  appearance  of  ivory  and  is  very  hard,  but  can  be 
turned  in  the  lathe. 

VEGETABLE  OIL  SEEDS — The  cakes  left  from  the  extraction 
of  oils  from  such  materials  as  copra,  cotton- seed,  ground- 
nuts, linseed,  palm- kernels,  rape-seed,  rice  bran,  rice  meal, 
sesame-seed,  soya-beans,  etc.,  are  employed  as  cattle  foods. 
(See  Oil  Cake.) 


VEGETABLE  TALLOW— VEGETO-ALKALOIDS      503 

VEGETABLE  TALLOW  (Chinese),  obtained  from  the  seeds  of 
Stillingia  sebifera  and  used  in  candle-making,  is  produced 
of  two  qualities,  "prima"  and  "secunda,"  having  sp.  grs. 
of  0-8843  t°  0*904  and  0*8928  respectively,  and  saponifica- 
tion  values  of  206  and  204.  The  "prima"  quality  melts 
at  36°  to  47°  C.  and  its  iodine  value  is  19*37  to  60*76, 
whilst  the  "secunda"  iodine  value  is  82*20. 

VEGETABLE  WAX  (Japan  Wax) — See  Waxes. 

VEGETATION — The  chemical  processes  involved  in  vegetable 
life  are  only  comparable  to  those  concerning  the  animal 
organism,  and  are  of  the  same  general  order.  Fed  upon 
water,  the  atmospheric  constituents,  and  the  matters  present 
in  soil,  the  list  of  vegetable  products  is  wide  and  wonderful. 
In  addition  to  the  cellulosic  compounds  constituting  the 
cells  and  vessels,  there  are  the  wide  range  of  colouring 
matters  (see  Plant  Colouring  Matters),  the  various  alka- 
loidal  bodies,  such  as  aconitine,  quinine,  and  morphine,  a 
range  of  carbohydrates,  including  starches  and  sugars,  a 
still  wider  range  of  essential  oils  and  other  volatile  principles, 
and  innumerable  chemical  products  having  medicinal  or 
commercial  value,  all  of  which  are  built  up  synthetically 
by  the  agency  (life-action)  of  the  nitrogenous  protoplasm. 

Vegetation  has  an  important  bearing  upon  the  health 
of  communities  as,  apart  from  the  capacity  of  plant  life 
for  absorbing  carbon  dioxide  from  the  air  and  restoring 
oxygen  thereto  (see  Carbon  and  Air),  trees  absorb  from 
the  soil  a  great  deal  of  water,  which  for  the  most  part 
is  subsequently  evaporated  into  the  air  from  the  surfaces 
of  the  leaves,  so  that  many  malarious  districts  can  be 
made  drier  and  more  healthy  by  means  of  plantations. 
Again,  many  plants  and  trees  give  off  essential  oils  into  the 
air  and  thus  exercise  a  beneficial  effect  due  to  their  balsamic 
character  and  the  subsequent  production  of  hydrogen  dioxide 
by  the  action  of  the  air  and  moisture  upon  these  oils. 
Vegetation  also  assists  in  the  purification  of  polluted  waters 
and  soils  by  utilizing  their  organic  constituents. 

As  a  rule,  plants  obtain  what  nitrogen  they  require  from 
the  ammonia  and  other  soluble  nitrogen  compounds  that 
are  present  in  the  air  and  soil,  the  ammonia  for  the  most 
part  coming  from  products  of  organic  decay;  but  some 
plants  of  the  leguminous  order,  such  as  peas  and  beans,  as- 
similate nitrogen  direct  from  the  air  by  some  action  of 
bacteria  situate  in  nodules  which  form  on  the  rootlets  of 
these  plants.  (See  Bacteria,  Carbon,  Fertilizers,  and  Soils.) 

VEGETO-ALKALOIDS— See  Alkaloids, 


504  VENETIAN  RED—VETIVER  OIL 

VENETIAN  RED — A  pigment  and  polishing-powder,  consisting 
of  ferric  oxide,  made  from  red  haematite  or  by  calcining 
ferrous  sulphate. 

VENICE  TURPENTINE—  See  Turpentine. 

VENTZKE  DEGREES  are  referable  to  a  determination  of  the 
sucrose  or  cane-sugar  content  of  a  solution  by  means  of  a 
polariscope,  the  scale  being  so  graduated  that  the  amount 
is  read  off  direct.  When  the  normal  weight  of  26-048 
grms.  of  sucrose  are  dissolved  in  100  c.c.  of  solution 
in  a  200  mm.  tube,  the  degree  registered  is  100  and  so  on. 

VERATRINE— This  is  really  a  mixture  of  alkaloids  obtained 
from  sabadilla  (cevadilla) — the  dried  ripe  powdered  seeds  of 
Schoenocaulon  officinale — by  exhausting  with  alcohol.  The 
chief  alkaloid  is  cevadine  (C32H49NO9),  also  termed  vera- 
trine,  and  it  is  accompanied  with  veratridine  (C37H53NOn). 
Cevadine  is  a  white,  crystalline  body  of  extremely  poisonous 
character,  soluble  in  alcohol  and  ether,  and  is  used  medicin- 
ally as  an  anti- febrile  agent.  (See  Sabadilla.) 

VERBENA  OIL  (sp.  gr.,  0-894  to  0-918  ;  rotation,  -  12°  to  -  16°) 
is  distilled  from  the  leaves  of  Verbena  tryphilla,  grown  in 
France  and  Spain,  and  contains  from  21  to  38  per  cent, 
of  citral.  The  Indian  oil  (lemon  grass)  comes  from  the 
grasses  Andropogon  citratus  (Ceylon  and  Straits  Settlements) 
and  A.flemosus  (Malabar  and  Cochin),  its  chief  constituent 
being  citrol.  Its  sp.  gr.  is  0-877  to  °'9°5  5  rotation,  +  3° 
to  -  3° ;  and  it  contains  from  75  to  85  per  cent,  citral. 

VERDIGRIS — A  poisonous,  green-coloured  basic  carbonate 
(CuCO3,Cu(HO)2)  which  forms  on  copper  when  exposed 
to  damp  air. 

VERMILION— See  Mercury  (Sulphide). 

VERMILION  SUBSTITUTE — A  preparation  which  has  largely 
supplanted  mercuric  sulphide,  consisting  of  about  95  per 
cent.  Pb3O4  coloured  with  eosin  (tetrabromo-fluorescin) — a 
red,  crystalline,  organic  dye. 

VERONAL— See  Barbitone. 

VESUVIAN  (Vesuvianite) — A  crystalline  mineral  consisting  in 
the  main  of  calcium-aluminium  silicate. 

VETIVER  OIL  (discus  Oil),  distilled  from  the  roots  of  Andro- 
pogon muricatus  and  used  in  perfumery,  is  a  thick  yellow  oil 
of 'an  odour  like  that  of  violets,  soluble  in  alcohol,  ether, 
etc./ and  of  sp.  gr.  about  I  -o. 


VI 'N EG  A  R—  VITA  MINES  505 

VINEGAR  is  a  preparation  of  acetic  acid,  of  which  it  contains  a 
legal  minimum  of  4  per  cent.  The  ordinary  English  variety  is 
made  by  the  method  referred  to  under  Acetic  Acid,  the 
British  production  being  estimated  at  15  million  gallons  per 
annum.  In  Germany  and  France,  it  is  made  from  wine 
by  exposure  to  the  air  in  casks  containing  some  beech- 
shavings  or  by  mere  exposure  to  the  air  in  sunlight. 

Malt  Vinegar  is  prepared  from  malt  or  malt  and  raw 
barley  mashed  as  in  brewing  and  then  submitted  to  vinous 
fermentation  and  subsequently  soured  as  already  described. 

Distilled  Vinegar  is  any  variety  of  vinegar  submitted  to 
distillation,  so  that  it  is  thereby  deprived  of  its  colouring 
matter. 

•  Tomato  Vinegar  is  simply  vinegar  flavoured  with  an 
infusion  of  tomatoes,  or  tomatoes  may  be  added  to  the 
alcohol  or  wine  before  acetification. 

VIOLET  ESSENCE— See  Orris  Oil. 
VISCOID— See  Silk,  Artificial. 
VISCOSE— See  Silk,  Artificial. 

VISCOSIMETER — An  instrument  or  apparatus  for  determining 
viscosity. 

VISCOSITY — The  viscosity  of  a  colloid  solution  is  ascertained 
by  measuring  the  time  of  outflow  from  a  standard  volu- 
metric pipette;  roughly  expressed,  the  viscosity  is  in- 
versely proportional  to  that  time.  The  viscosity  of  oils 
and  greases  is  determined  in  much  the  same  way,  or  by  the 
time  taken,  under  standardized  conditions,  for  a  metallic 
bulb  to  fall  through  a  measured  column  of  the  substance 
under  examination. 

VISCOUS — Thick,  sticky,  glutinous,  ropy. 

VITAMINES  (Accessory  Food  Factors) — The  name  given  to 
some  mysterious  soluble  substances  of  nitrogenous  nature 
present  in  certain  living  tissues  and  products,  including 
butter  and  cod-liver  oil,  but  absent  from  lard  and  nut  and 
seed  oils  after  they  have  been  hydrogenized.  In  butter 
they  are  contained  in  the  less  crystallizable  part  known 
as  butter  oil.  One  class  (A)  is  soluble  in  fat  solvents, 
a  second  class  (B)  is  soluble  in  water  but  not  in  fat  solvents, 
and  a  third  class  (C)  is  soluble  both  in  water  and  alcohol. 
They  are  supposed  to  have  great  influence  in  the  promotion 
of  growth,  as  although  they  exist  in  very  small  amounts,  they 
exercise  an  influence  like  that  of  enzymes  in  converting  what 
would  otherwise  be  non-efficient  dietaries  into  efficient  ones  . 


5o6  VITAMINES-"  VITREOSIL  " 

VITAMINES  (Continued)— 

It  has  been  stated  that  the  fresh  juices  of  the  edible 
parts  of  the  orange,  lemon,  and  grape-fruit  contain  water- 
soluble  so-called  B-vitamine  equivalent,  volume  for  volume, 
with  cow's  milk,  grape-juice  being  inferior  in  this  respect ; 
and  that  the  edible  parts  of  apples  and  pears  furnish  some 
quantity,  but  are  not  rich  in  this  respect,  while  prunes  are 
somewhat  richer.  Further,  that  lard,  palm,  yellow  maize, 
and  cotton-seed  oils  apparently  contain  appreciable  amounts 
of  the  fat-soluble,  growth-promoting  substance,  and  that 
cabbages  and  potatoes  both  contain  the  fat-soluble  factor, 
which  can  be  extracted  by  alcohol,  raw  cabbages  being 
particularly  rich.  Crude  unrefined  cod-liver  oil  is  said  to 
be  250  times  as  potent  as  butter,  whilst  swedes  are  very 
rich  in  the  antiscorbutic  vitamine  (C). 

In  the  absence  of  the  fat-soluble  vitamine  (A)  normal 
nutrition  is  deficient. 

The  disease  known  as  beri-beri,  which  is  endemic  in 
Japan,  the  Malay  Peninsula,  and  the  Dutch  Indies,  has 
been  attributed  to  the  habit  of  feeding  too  exclusively  upon 
polished  rice,  due  to  the  removal  of  the  constituent  water- 
soluble  B-vitamine  which  is  associated  with  the  "  silver 
skin  "  of  the  seed,  and  which  is  unfortunately  removed  by 
the  milling  process  now  prevalent  for  polishing  the  rice. 
Similarly,  soldiers  or  sailors  who  for  long  periods  are 
unable  to  obtain  supplies  of  fresh  foods  are  liable  to  scurvy, 
and  probably  for  a  similar  reason,  as  this  disease  can  be 
prevented  by  the  use  of  fresh  meat  and  vegetables  and  of 
orange  and  lemon  juices,  all  of  which  contain  the  vitamines 
of  class  C.  The  antiscorbutic  vitamine  is  stated  to  be 
very  sensitive  to  alkaline  reaction,  and  is  completely 
destroyed  by  heat,  unless  associated  with  an  acid  which 
greatly  protects  it  in  this  respect,  so  that  the  tomato,  for 
instance,  is  antiscorbutic  even  after  canning.  Diets  may 
be  perfectly  wholesome  and  perfectly  digested,  but  unless 
the  food  is  associated  with  a  proper  proportion,  small 
as  it  is,  of  vitamines  derived  from  living  cells  of  plants  or 
animals,  the  nutrition,  particularly  of  the  nervous  system, 
is  defective. 

Egg-yolk,  milk,  butter,  cabbages,  potatoes,  edible  pulses, 
spinach,  yeast,  and  the  germs  and  cells  of  cereals  are  all 
good  vitamine-carrying  foods  when  fresh.  (See  Foods  and 
Hormones.) 

"VITREOSIL" — A  trade  proprietary  name  for  pure  fused 
silica  used  in  making  laboratory  ware  heat  and  acid  proof, 
and  of  opaque,  translucent,  and  transparent  qualities. 


VITREOUS—"  VOLTOL"  OILS  J  507 

VITREOUS— Glassy. 

VITRIOL  or  OIL  OF  VITRIOL— Strong  sulphuric  acid  (See 
p.  468.) 

VIVIANITE— A  mineral  ferrous  phosphate. 

VOLATILE — Light,  ethereal,  easily  passing  from  the  liquid 
to  the  gaseous  state 

VOLTAMETER — An  apparatus  for  the  electrolysis  of  water 
— that  is,  its  decomposition  by  means  of  an  electric 
current.  A  simple  form  (as  illustrated)  consists  of 
an  inverted  funnel-head,  the  neck  of 
which  is  closed  with  a  cork  or  com- 
position through  which  are  passed 
two  platinum  wires  terminating  above 
in  small  plates  of  the  same  metal. 
The  funnel  is  partly  filled  with  water, 
and  over  the  upright  platinum  plates, 
two  test-tubes  filled  with  water  acidu- 
lated with  a  little  sulphuric  acid  (to 
assist  the  passage  of  the  electric  cur- 
rent) are  inverted.  On  connecting  the 
wires  with  a  battery  of  three  or  four 
cells  the  current  passes,  and  by  de- 
composition of  the  water  causes  the 
production  of  2  volumes  (parts)  of 
hydrogen  gas  in  the  one  tube  and  i  volume  (part)  of  oxygen 
gas  in  the  other.  (See  also  Eudiometer.) 

"  VOLTOL  "  OILS — Oils  such  as  rape  and  marine  animal  oils, 
thickened  by  blowing,  followed  by  electrical  treatment  (the 
high  viscosity  thus  secured  being  due  to  oxidation  and 
polymerization),  and  used  amongst  other  applications  for  ad- 
mixture with  mineral  oils  to  be  used  as  lubricants,  in  the 
place  of  castor  oil.  The  following  information  is  taken 
from  a  recent  article  in  the  Chemical  Age  (December 
n,  1920)  : 


A  Voltameter. 


Sp.Gr. 

Refractive 
Index 
at  15°  C. 

Viscosity 
at  100°  C. 

Acid 
Number. 

Iodine 
Number. 

Mean 
Molecular 
Weight. 

Rape  voltol 
Whale  voltol  ... 

0-9740 
0*9819 

I-485 
IHSS 

83-6 
74'9 

II'7 
i5'4 

52 
51 

I20O 
1000 

5o8        "VOLTOL"  OILS— VOLUMETRIC  ANALYSES 

"VOLTOL"  OILS  (Continued)— 

The  high  viscosity  of  voltol  oils  is  due  in  part  to  the  con- 
tained oxidation  products  and  polymerization  induced  by 
the  blowing,  but  chiefly  to  the  production  of  di-molecular 
glycerides  under  the  influence  of  the  electric  discharge, 
thus  accounting  for  the  high  molecular  weights. 

VOLUMETRIC  ANALYSES  —  Methods  of  determining  the 
amounts  of  chemical  substances  present  in  solutions,  by 
the  employment  of  reagents  of  definite  strength  in  connec- 
tion with  well-understood  interactions.  To  determine, 
for  example,  the  amount  of  free  iodine  contained  in  an 
acidified  solution  of  potassium  iodide,  a  standardized 
solution  of  sodium  hyposulphite  is  employed — that  is  to 
say,  a  solution  of  predetermined  strength — and  this  is 
gradually  run  into  the  subject  mixture,  from  a  burette  until 
the  colour  has  entirely  disappeared.  It  is  then  easy  to 
calculate  from  the  known  chemical  interaction  that  takes 
place  the  amount  of  free  iodine  in  the  mixture.  The  inter- 
action is  represented  as  follows  : 

I2  +  2Na2S2O3  =  2NaI  +  Na2S4O6 

that  is  to  say,  the  free  iodine  is  converted  into  potassium 
iodide  and  the  sodium  hyposulphite  into  sodium  tetrathion- 
ate,  and  knowing  the  amount  of  hyposulphite  consumed 
it  is  easy  to  calculate  the  amount  of  free  iodine  changed  as 
explained. 

If  a  little  starch  solution  be  added  to  the  iodine  solution 
just  before  the  completion  of  the  titration,  a  beautiful  blue 
colouration  is  produced,  and  this  is  generally  done  in  practice 
as  it  is  so  much  more  evident  than  that  of  the  uncombined 
iodine  colouration. 

For  the  determination  of  the  amount  of  alkali  or  acid 
present  in  solutions,  calculations  are  made  based  upon  the 
amount  of  standardized  solutions  of  acid  or  alkali  required 
respectively  by  titration  to  neutralize  them,  this  point  of 
neutrality  being  ascertained  by  means  of  an  indicator,  or 
substance  which  undergoes  a  marked  change  of  colour 
upon  the  change  from  alkalinity  to  acidity  or  vice  versa. 
The  indicators  chiefly  used  are  methyl  orange,  phenol- 
phthalein,  and  litmus.  Others  are  aurin,  cochineal,  cur- 
cumin  (turmeric  yellow),  gallein  (alizarin  violet),  iodoesin 
(prepared  by  iodating  fluorescein),  lacmoid  (resorcin  blue), 
and  methyl  red. 

Methyl  orange,  lacmoid,  cochineal,  and  iodoesin  are  in- 
sensitive to  weak  acids ;  litmus  is  typical  of  the  indicators 


VOLUMETRIC  ANALYSES— WALNUT  OIL  509 

VOLUMETRIC  ANALYSES  (Continued}— 

somewhat  sensitive  to  weak  acids ;  and  phenolphthalein, 
turmeric,  and  rosolic  acid  are  highly  sensitive  to  weak 
acids. 

Methyl  orange  dissolved  in  water  is  turned  yellow  by 
alkalies  and  pink-red  by  acids. 

Phenolphthalein  dissolved  in  alcohol  is  colourless,  but 
alkalies  turn  it  to  a  deep  red  colour,  which  is  at  once 
discharged  by  acids. 

In  the  precipitation  of  anthranilic  acid  (amino-benzoic 
acid)  from  its  alkaline  solution  by  addition  of  mineral  acid, 
an  acid  reaction  to  methyl  red  indicates  the  approach  of 
the  end-point,  a  further  addition  of  acid  indicating  the  point 
of  maximum  precipitation  is  shown  by  the  acid  reaction  to 
thymol  blue. 

Thymolsulphophthalein  is  said  to  be  a  useful  indicator 
in  the  liming  of  sulphonation  mixtures,  a  red  colouration 
indicating  that  free  acid  is  still  present.  When  the  in- 
dicator shows  a  yellow  colour  the  end-point  is  near,  and  a 
blue  colour  shows  that  the  mixture  is  alkaline, 

Dibromocresolsulphophthalein  or  dibromothymolsulpho- 
phthalein  may  be  used  as  substitutes  for  litmus,  the  former 
changing  from  yellow  to  purple  and  the  latter  from  yellow 
to  blue. 

Other  volumetric  methods  are  based  upon  processes  of 
oxidation,  reduction,  and  precipitation.  (See  also  Burette, 
Litmus,  Reagents,  and  Turmeric  Paper.) 

VRIAC— A  French  term  for  kelp. 

VULCANITE  is  made  by  heating  2  parts  of  india-rubber  with 
i  part  of  sulphur  to  a  temperature  of  about  150°  C.,  and  is 
largely  used  for  making  pumps,  taps,  tubing,  and  unions 
for  use  in  chemical  works,  as  also  for  combs  and  other 
articles.  Gutta-percha  is  vulcanized  in  the  same  way. 
(See  Rubber.) 

VULCANIZATION— See  Rubber. 

WALNUT  OIL,  expressed  from  the  seeds  of  Juglans  regia,  is  of 
pale  yellowish-green  colour,  with  sp.  gr.  0-92  to  0-93  ;  refrac- 
tive index,  1-4808;  saponification  value,  192  to  197;  and 
iodine  value,  142  to  146.  The  main  constituent  is  linolic 
acid.  It  is  soluble  in  alcohol  and  ether  and  is  used  in  the 
varnish  and  paint  trades. 


5io  WA  SH-BOTTLE—  WA  TER 

WASH-BOTTLE — A  flask  fitted  with  a  cork  or  rubber  stopper 
having    two    borings,   through  which   pass    bent    tubes : 
a  short  one  terminating  just  below  the  stopper,  while  the 
other  goes  nearly  to  the  bottom  of  the  flask  and  terminates 
at  the  outside  end  in  a  drawn-out  point,  so  that 
when  in  use  (as,  for  instance,  washing  a  pre- 
cipitate upon  a  filter)  the  water  emerges  there- 
from in  a  fine  stream. 

By  applying  the  mouth  to  the  short  tube  and 
blowing,  the  water  is  forced  out  of  the  flask 
through  the  longer  tube.  In  other  cases,  wash- 
bottles,  instead  of  being  filled  with  water,  are 
charged  with  alcohol,  ether,  or  other  solvent, 
according  to  the  solubilities  of  the  substances  to 
be  removed  from  the  subject-matter  of  the 
washing. 

Appliances  similarly  constructed,  using  either 
flasks  or  bottles,  are  also  used  for  washing  gases,  the  gas 
being  passed  or  drawn  through  the  liquid  contents  by  the 
long  tube,  and  the  washed  gas  escaping  through  the  shorter 
tube.  (See  Aspirator.) 

WASHING  SODA-  See  Sodium  Carbonate,  p.  443. 

WATER  (H2O) — Molecular  weight,  18.  Water  is  known  to 
all,  in  the  various  forms  of  rain,  snow,  ice,  and  steam ;  but, 
unlike  the  air  we  breathe  (which,  it  will  be  remembered,  is 
a  mechanical  mixture),  water  is  a  real  chemical  compound 
and  consists  or  is  made  up  of  the  two  elements,  hydrogen 
and  oxygen. 

Hydrogen  and  oxygen  in  their  ordinary  state  are  both 
gases;  but  when  they  are  made  to  combine — as,  for  example, 
by  the  agency  of  electricity — they  form  water. 

Two  parts  of  hydrogen  (H)  by  volume  combine  with 
i  part  or  volume  of  oxygen  (O)  and  make  water,  which 
chemists  symbolize  with  the  lettering  H2O,  which  shows 
that  water  is  composed  or  made  up  of  2  atoms  hydrogen 
and  i  atom  oxygen. 

Water  boils  at  100°  C.  (212°  F.)  and  freezes  at  o°  C. 
(32°  F.)  to  a  crystalline  solid  having  a  sp.  gr.  of  0-93.  It 
attains  its  maximum  density  at  4°  C.  (See  footnote, 
p.  240.) 

In  its  several  forms,  water  makes  up  about  three-quarters 
of  the  materials  constituting  the  surface  of  the  earth.  It 
also  enters  largely  into  the  composition  of  the  tissues  of 
vegetables  and  animals — to  the  extent  of  from  80  to  90  per 
cent. 


WATER  511 

WATER  (Continued}— 

It  has  greater  solvent  power  than  any  other  liquid  in 
respect  of  variety  of  substances,  and  enters  largely  into  the 
composition  (constitution)  of  many  chemical  substances, 
such  as  hydrates  and  salts,  being  combined  in  the  last- 
named  substances  as  water  of  crystallization.  Copper 
sulphate,  for  example,  crystallizes  in  a  form  containing 
5  molecules  of  water  (CuSO4,5H2O)  and  magnesium  sulphate 
with  7  molecules  (MgSO4,7H2O). 

Sodium  chloride  is  known  in  two  crystalline  forms — viz., 
NaCl,2H2O  and  NaCl,ioH2O:  whilst  sodium  carbonate  is 
known  in  chemical  association  with  water  in  several  forms, 
including  Na2CO3,ioH2O,  Na2CO3,7H2O,  and  Na2CO3, 
H2O,  and  so  forth. 

In  many  cases,  the  colours  of  salts  are  dependent  upon 
the  amount  of  water  of  crystallization,  as  instanced  by 
cobalt  chloride  (CoCl2,6H2O),  which  is  pink,  but  when 
gently  heated  to  120°  C.  becomes  blue  in  colour  by  the  loss 
of  its  water — hence  the  employment  of  the  pink  compound 
in  the  preparation  of  so-called  sympathetic  inks,  the  faintly 
pink  written  words  becoming  visibly  blue  upon  warming  of 
the  paper  on  which  they  are  written. 

Another  compound — viz.,  magnesium  platino-cyanide 
— in  its  crystalline  form  contains  7  molecules  of  water 
(MgPt(CN)4,7H2O)  and  is  of  a  bright  scarlet  colour,  but 
when  heated  to  50°  C.  it  loses  2  molecules  of  water  and  be- 
comes MgPt(CN  )4,5H2O,  which  is  of  a  canary-yellow  colour, 
and  upon  raising  the  temperature  to  100°  C.  a  white  salt 
finally  results,  having  the  composition  MgPt(CN)4,2H2O. 
(See  also  Efflorescence  and  Deliquescence.) 

Sea  water  is  impregnated  with  salts  washed  out  of  the 
earth's  surface  ;  has  a  sp.  gr.  of  about  1*025  to  1-027,  as 
compared  with  ordinary  water,  i-o;  and  contains  large 
quantities  of  common  salt  and  magnesium  chloride.  The 
water  of  the  British  Channel  contains  28-05  parts  NaCl, 
3-66  parts  of  MgCl2,  and  47  parts  of  other  mineral  sub- 
stances in  each  1,000  parts. 

Rain-water,  as  collected  in  country  places  where  the  air 
is  not  fouled  with  smoke  and  other  emanations,  is  as  nearly 
pure  as  it  can  be  found  in  nature,  but  even  then  it  contains 
about  2j  volumes  of  air  dissolved  in  each  100  volumes  by 
measure. 

Water  as  given  off  from  the  lungs  in  respired  air  by 
adults  in  twenty-four  hours  has  been  estimated  at  an 
average  of  311  grms.,  or  nearly  n  ounces. 

When  water  is  boiled  it  takes  the  form  of  steam,  which 


512  WATER— WATER  GAS 

WATER  (Continued)— 

is  its  gaseous  state,  and  when  this  is  again  cooled, 
it  becomes  condensed  as  water  once  more,  and  is 
known  as  distilled  water.  Steam  is  an  effective  germ 
destroyer,  and  there  are  a  number  of  so-called  disinfectors 
or  destroyers  in  which  it  is  generated  and  used  for  the 
disinfection  of  clothing  and  bedding. 

Rain  water  is  a  sort  of  distilled  water.  The  heat  of  the 
sun  evaporates  water  from  the  earth  and  the  sea,  and  then, 
when  the  air  is  more  or  less  saturated  with  the  water 
vapour  and  becomes  cold  enough,  it  is  transformed  and 
falls  as  rain,  or  snow,  or  hail. 

Water,  as  ordinarily  supplied  for  drinking  purposes, 
contains  impurities  in  the  form  of  substances  dissolved  out 
of  the  earth  with  which  it  comes  naturally  into  contact, 
and  supplies  are  roughly  classified  as  "hard"  or  "  soft"  in 
character.  The  so-called  "  temporary  hardness  "  is  mainly 
derived  from  the  presence  of  calcium  carbonate  or  chalk  in 
solution,  which  is  deposited  as  a  fur  or  cake  in  tea-kettles  and 
boilers.  This  deposition  is  due  to  the  expulsion  of  carbon 
dioxide,  also  contained  in  the  water,  and  which  by  its 
presence,  and  until  expelled  by  the  heat,  holds  the  chalk  in 
solution.  Such  waters  may  be  softened  to  some  extent 
by  boiling,  or  by  the  addition  of  lime,  which,  by 
entering  into  combination  with  the  carbon  dioxide,  forms 
insoluble  calcium  carbonate  (CaO +  CO2=CaCO3),  which 
is  deposited  along  with  the  carbonate  previously  held  in 
solution  by  the  carbon  dioxide  thus  removed. 

The  "  permanent  hardness  "  of  natural  waters  is  largely 
due  to  the  presence  in  solution  of  the  sulphates  of  calcium 
and  magnesium,  the  degree  of  hardness  being  dependent 
upon  the  nature  of  the  geological  formation  in  which  the 
water  is  found. 

The  "  Permutit "  system  of  water-softening  is  referred 
to  under  that  heading.  Many  gases  are  soluble  in  water 
to  some  extent,  including  nitrogen,  oxygen,  carbon  dioxide, 
and  argon,  the  degree  varying  with  the  temperature,  etc. 

Soft  water  is  water  which  is  more  or  less  devoid  of  sub- 
stances held  in  solution,  so  that  freshly  collected  rain  water 
is  quite  soft  in  character.  (See  also  Filters.) 

WATER  GAS  is  obtained  by  passing  steam  over  red-hot  coke, 
which  has  the  effect  of  decomposing  the  water- vapour  and 
producing  a  mixture  of  hydrogen  and  carbon  monoxide 
gases— 


WATER  GAS— WAXES 


513 


WATER  GAS  (Continued)— 

To  make  this  mixture  of  gases  (which  otherwise  burns 
without  flame  when  lighted)  luminous  when  burning,  it  is 
mixed  with  oil  vapours,  and  it  is  also  employed  for  mixing 
with  ordinary  coal  gas.  (See  Coal  Gas  and  Producer  Gas.) 

WATER-GLASS— See  Silica,  p.  431. 

WATER-OVEN— An  appliance,  as  illustrated  in  the  figure,  in 

which  it  is  possible 
to  dry  chemical  sub- 
stances (in  suitable 
containers)  at  100°  C., 
consisting  of  a  water- 
jacketed  copper  box 
which  can  be  heated 
by  a  lamp  placed  below. 
A  vent  is  provided  for 
the  escaping  steam  and 
for  charging  the  jacket 
with  water, and  through 
the  other  opening  on 
the  top,  a  thermometer 
fitted  with  a  cork  may 
be  placed.  The  figure 
shows  such  an  oven 
connected  with  a  con- 
denser for  the  escaping 
steam,  which  may  be  thus  made  to  furnish  a  supply  of 
distilled  water. 

WATTLE— Bark  from  the  Australian  wattles  Acacia  pycnantha, 
A.  mollissima,  and  A.  binervata,  used  in  tanning.  (See 
Tannins.) 

WAVELLITE— A  native  aluminium  phosphate  (2A12(PO4)2, 
A12(HO)6,9H20). 

WAXES — There  are  many  waxes  of  mineral,  animal,  and  veget- 
able origin,  of  which  the  best-known  variety  is  Beeswax, 
produced  by  bees  from  the  sugar  of  their  food.  It  is  some- 
what yellow,  tough  and  solid,  and  can  be  bleached  by 
chlorine.  It  is  of  complex  composition,  and  contains 
several  different  substances  including  myricin  (myricyl 
palmitate,  or  the  melissic  ester  of  palmitic  acid,  C46H9,O2) 
and  free  cerotic  acid  (C26H62O2) — one  of  the  normal  fatty 
acids.  It  melts  at  63°  C.  ;  its  sp.  gr.  is  0-96  to  0*97 ;  it  is 
soluble  in  alcohol,  ether,  and  chloroform,  and  is  used  in 
making  candles  and  various  polishes. 

33 


514  WAXES 

WAXES  (Continued)— 

Bay-berry  Wax,  from  the  bark  of  the  Myrica  ( Candle- 
berry,  Bay-berry,  Wax-berry),  is  green  in  colour,  and  con- 
sists of  palmitin,  palmitic  acid,  myristin,  and  lauric  acid. 
It  is  used  in  candle-making. 

Candelilla  Wax  is-  found  as  an  excretion  on  Euphorbia 
cerifera  and  E.  antisyphilitica  (plants  growing  in  North 
Mexico  and  southern  parts  of  the  United  States),  from 
which  it  is  obtained  by  boiling  them  in  water  and  adding 
some  sulphuric  acid.  It  is  used  in  making  polishes, 
candles,  sealing  wax,  etc.  It  is  opaque  to  translucent, 
melts  at  about  67°  C.,  has  a  sp.  gr.  of  0-983,  and  an  iodine 
value  of  37. 

Carnauba  Wax  is  obtained  from  the  leaves  of  a  palm 
(Copernica  cerifera)  in  Brazil,  they  being  coated  with  this 
yellowish -white  exudation,  which  melts  at  84°  to  86°  C.,  and 
in  many  respects  resembles  beeswax,  for  which  it  is  used 
for  some  purposes  as  a  substitute.  Its  sp.  gr.  is  0-995, 
and  it  is  soluble  in  alcohol  and  hot  ether. 

Ceresine  is  a  white  wax-like  substance  of  mineral  character 
obtained  by  purification  of  ozokerite,  consisting  of  treatment 
with  strong  sulphuric  acid,  followed  by  filtration  in  a  melted 
condition  through  animal  charcoal.  It  is  used  in  candle- 
making  and  as  a  substitute  for,  or  admixture  with,  bees- 
wax ;  has  a  sp.  gr.  of  0-92  to  0-94,  melts  at  74°  to  80°  C., 
and  is  soluble  in  alcohol,  benzol,  etc. 

Chinese  Wax  (Pela),  or  vegetable  insect  wax,  is  formed  on 
the  branches  of  a  species  of  ash-tree  (Fraxinus  chinesis)  by 
the  puncture  of  the  coccus  insect  (Coccus  ceriferus).  It 
resembles  spermaceti ;  consists  for  the  most  part  of  a  sub- 
stance named  cerobylic  or  ceryl  cerotate,  and  is  used  in 
China  for  candle-making.  It  admits,  like  the  fats,  of 
saponification  with  potash  ;  is  white  to  yellowish  in  colour, 
of  sp.  gr.  of  0-970,  melts  at  80°  to  83°  C.,  and  is  soluble 
in  alcohol,  benzol,  and  chloroform. 

Coca  Wax  (C33H66O2)  is  obtained  from  the  leaves  of  the 
Ery thro xy Ion  coca  plant  cultivated  in  Peru,  Bolivia,  and 
Brazil,  and  which  are  used  for  chewing  like  tobacco  (see 
also  Cocaine).  After  purification,  it  is  a  white  amorphous 
substance  which  melts  at  70°  C.  and  is  readily  soluble  in 
hot  alcohol. 

Cotton-Seed  Wax — Contained  in  raw  cotton  to  the  extent 
of  about  0-5  per  cent. 


WAXES  515 

WAXES  (Continued)— 

Cow-Tree  Wax  is  obtained  by  evaporating  the  milk  of  the 
cow-tree  (Palo  de  vaca,  Brosunum  galactodendron).  It  resembles 
beeswax  in  some  general  characters  and  admits  of  saponi- 
fication. 

Godang  Wax  (Getah  Wax)  is  made  from  the  latex  of  a 
wild  fig-tree  (Ficus  cevuflua  or  F.-  subracemosa). 

Japan  or  Vegetable  Wax,  or  tree  wax,  is  partly  obtained 
in  the  East  Indies  from  berries  of  the  Rhu$  succedanea 
and  several  species  of  sumach-tree  by  boiling  the  fruit 
in  water.  It  is  not  a  real  wax  but  a  glyceride,  and  con- 
tains palmitin  with  free  palmitic  acid.  It  has  a  yellow 
colour,  is  soluble  in  benzol  and  naphtha,  melts  at  53°  C.,  and 
is  of  sp.  gr.  0*970  to  0*980.  The  Island  of  Kyushu  accounts 
for  about  one-half  of  the  total  production  obtained  from 
the  fruit  kernels  of  a  tree  peculiar  to  Japan.  It  is  used 
in  making  wax  matches,  candles,  furniture  polish,  and 
leather-dressing. 

Montan  Wax  is  extracted  from  pyropissite  obtained  from 
the  lignites  of  Saxony  and  Thuringia.  When  refined  it  is 
white,  and  is  used  as  a  substitute  for  carnauba  wax.  It  is 
soluble  in  benzol,  chloroform,  and  carbon  tetrachloride. 

Ocuba  Wax  is  obtained  from  the  fruit  of  Myristica  ocuba 
officinalis,  which  grows  in  marshy  ground  on  the  Amazon 
shores,  and  is  used  in  Brazil  for  making  candles. 

Paraffin  Wax  is  made  from  ozokerite  by  treatment  with 
sulphuric  acid  and  subsequent  bleaching,  and  is  also  a 
solid  constituent  of  the  oily  distillates  from  natural  bitu- 
minous substances,  including  coal,  shale,  lignite,  peat,  wood, 
and  natural  petroleum,  from  which  it  is  obtained  by  re- 
frigeration. It  is  a  white  translucent  mixture  of  hydro- 
carbons of  sp.  gr.  0-880  to  0-915,  and  melts  between 
45°  and  65°  C. 

It  is  soluble  in  turpentine,  benzol,  carbon  disulphide, 
and  chloroform,  and  comes  into  the  market  in  many 
grades,  some  hard  and  some  soft,  all  known  as  "  paraffin 
scale"  before  purification,  and  is  extensively  used  in  the 
manufacture  of  candles,  floor  polishes,  waxed  paper,  lubri- 
cants, waterproofing  of  wood  and  cprks,  etc. 

By  oxidation  at  150°  C.  in  a  stream  of  oxygen  and  in 
presence  of  manganese  compounds  it  is  by  catalytic  action 
largely  resolved  into  fatty  acids,  the  resulting  mass  con- 
taining 35  per  cent,  insoluble  in  water,  and  about  25  per 
cent,  of  lower  fatty  acids  (up  to  C10). 


516  WAXES 

WAXES  (Continued)— 

Palm  Wax  comes  from  the  Ceroxylon  andicola,  a  palm 
indigenous  in  the  tropical  parts  of  America,  on  the  stem 
of  which  it  forms  a  covering.  In  Ecuador,  trees  are  found 
in  great  numbers,  each  of  which  furnishes  about  50  Ibs. 
of  wax.  After  washing  with  hot  water,  in  which  it  does 
not  melt,  it  is  mixed  with  a  little  tallow  and  made  into 
balls  for  exportation.  It  is  yellow,  and  really  consists  of  a 
wax  and  resin  which  are  separated  by  hot  alcohol,  the  resin 
remaining  in  solution  and  the  wax  separating  out  as  a  jelly 
on  cooling.  When  purified  in  this  way  it  resembles  bees- 
wax in  appearance  and  composition. 

Pisang  Wax,  a  powdery  mass  obtained  from  the  leaves  of 
the  Cera  miisa,  indigenous  in  Java. 

Raphia  Wax  is  found  as  a  whitish  layer  on  the  under 
sides  of  the  leaves  of  a  Madagascar  palm.  The  dried 
leaves  yield  about  10  per  cent.  Its  sp.  gr.  is  0-834,  melt- 
ing-point 82-5°  C.,  saponification  value  51,  and  iodine 
value  from  7-7  to  10-7. 

Spermaceti,  an  ester  (cetyl  palmitate,  CleH33O.CO.C15H31 
or  C32H64O2).  It  is  a  pearly  white,  fatty  substance  found 
in  certain  cavities  of  the  head  of  the  sperm  whale  (Physetev 
macYocephalns)  and  in  smaller  quantity  in  the  blubber  of 
the  Balana  ro strata.  It  is  soluble  in  carbon  disulphide 
and  ether,  is  apt  to  become  rancid  when  exposed  to  light, 
has  a  sp.  gr.  of  0-929,  melts  at  from  44°  to  47*5°  C.,  and 
is  associated  with  sperm  oil,  from  which  it  has  to  be 
freed  before  it  attains  the  scaly,  brittle,  soft  character  of 
the  commercial  article.  Amongst  other  applications  it  is 
used  in  the  manufacture  of  candles,  soaps,  and  ointments. 

Sugar- Cane  Wax,  a  by-product  in  the  sugar  manufacture, 
obtained  from  the  canes — particularly  the  violet  species — 
by  scraping  or  skimming  off  the  juice  resulting  from  boiling 
them  out.  It  is  hard,  yellow,  granular,  soluble  in  hot 
alcohol  and  benzene,  melts  at  82°  C.,  and  has  a  sp.  gr. 
of  0-961.  It  appears  to  contain  45  per  cent,  of  myricil 
alcohol  (C30H62O)  and  another  substance  (C33H68O)  asso- 
ciated with  palmitic  and  stearic  acids.  It  is  extracted  in 
Java. 

Wool  Wax  appears  to  be  refined  wool  grease.  Its  sp.  gr. 
is  0*94,  it  melts  at  35°  C.,  saponification  value  102,  iodine 
value  25,  and  refractive  index  1-48.  (See  Suint.) 


WAXES—  WEIGHTS  AND  MEASURES 


517 


WAXES  (Continued)— 

APPROXIMATE  TYPICAL  VALUES  OR  CONSTANTS. 


Name. 

Specific 
Gravity. 

Melting- 
Point. 

Iodine 
Value. 

Saponi 
fication 
Number. 

Beeswax 

0-965-0-97 

63°-64°  C. 

9 

95 

Candelilla     ... 

0*94-0-983 

67°-68°  C. 

37 

46-65 

Carnauba 

Q'995 

84°-86°  C. 

13 

80 

Ceresine 

0-92-0-94 

74°-8o°  C. 

Chinese 

0-97 

8o°-83°  C. 

i  '4 

80-93 

Coca 

70°  C. 

Japan 
Montan 

0-970-0-980 

53°  C. 
72-77°  C. 

6 

220 

Myrtle 

0-99 

o         °  P 

i  '95 

208 

Ocuba 

0-92 

39*4° 

Paraffin 

o'88-o'O9i5 

45°-65°  C. 

Spermaceti   .  .  . 

0-945-0-96 

43°-47°  C. 

3'5-4'o 

122-130 

Sugar-Cane  ... 

0-968 

55°  C. 

60 

1  68 

WEIGHT  —  The  force  by  which  the  mass  of  a  substance  is 
attracted  by  gravity,  varying  therefore  according  to  the 
altitude  where  the  weight  is  determined. 

WEIGHTS — See  Scales  and  Weights  and  Measures. 

WEIGHTS  AND  MEASURES— The  weights  and  measures  used 
for  the  most  part  by  chemists  are  those  of  the  decimal  or 
metric   system,  and  the   chief  factors   and  their  English 
equivalents  are  as  follows  : 
Capacity : 

i  litre  =1,000  cubic  centimetres  =  35  J  English 
ounces  or  1-76077  pints;  and  there  are  about 
4^  litres  to  the  English  gallon. 

i  cubic  centimetre  (i  c.c.)  is  equal  to  15*43  grains  of 
water  at  4°  C.,  and  is  the  standard  of  the  French 
or  metric  system  of  weights  and  measures, 
i  gallon  =  70,000  grains  =  10  Ibs.  avoirdupois  weight 

of  water  and  4*5366  litres. 
Weight  : 

i  gramme  (or  gram)  is  the  weight  of  i  cubic  centi- 
metre (i  c.c.)  of  water  at  4°  C. 
i  milligram  is  the  i.oooth  part  of  a  gramme, 
i  centigram  is  the  looth  part  of  a  gramme. 


518  WEIGHTS  AND  MEASURES 

WEIGHTS  AND  MEASURES  (Continued)— 

i  decigram  is  the  loth  part  of  a  gramme. 

1,000  grammes  =  i  kilogramme. 

i  English  Ib.  =  454*43   grammes,  and  i  oz.  =  28*35 

grammes. 

i  gramme  =  15*43235  English  grains. 
i  Ib.  =  7,000  grains, 
i  gallon  of  water  =  10  Ibs. 
i  cubic  foot  of  water  =  62*321  Ibs. 

Length  : 

The   abbreviation   mm.    stands    for   millimetre,   or   the 
i,oooth  part  of  a  metre. 

25  mm.  =  i  inch. 

i  metre  =39*37  English  inches. 

i  kilometre  =  1,000  metres  or  about  1,100  English 

yards. 

i  decimetre  =  the  loth  part  of  a  metre, 
i  centimetre  =  the  looth  part  of  a  metre, 
i  millimetre  =  the  i,oooth  part  of  a  metre. 


Avoirdupois  Weights : 

1 6  drams  =  i  oz. 
1 6  ozs.  =  i  Ib. 
112  Ibs.  =  i  cwt. 
20  cwts.  =  i  ton. 


Apothecaries'  Weights  : 

20  grains  =  i  scruple  (  B). 

3  scruples  =  i  drachm  (3). 

8  drachms  ^  i  ounce  (§). 
12  ounces =  i  Ib. 


British  Pharmacopoeia  (Capacities) : 

i  minim  =  i  drop  (n\). 

60  minims  =  i   fluid   drachm   (fl.  drm.)  (3),  (i  tea- 
spoonful). 

8  fluid  drachms  =  i  fluid  ounce  (fl.  oz.)  (g),  (2  table- 
spoonfuls). 

20  fluid  ounces  =  i  pint  (O.) 
8  pints  =  i  gallon  (C.) 

Other  Useful  Data : 

To  reduce  kilogrammes  to  Ibs.  multiply  by  2*2046. 
To  reduce  litres  to  gallons  „          „  0*22. 

To  reduce  grammes  to  grains         „          „   i5*432- 
To  reduce  grains  to  grammes         ,,          ,,  0*0648. 
To  reduce  ounces  to  grammes        „          „  28*349. 
i  inch  =  2*539954  centimetres, 
i  foot  =  3*0479449  decimetres, 
i  yard  =  0*91438348  metre, 
i  mile=  1*6093149  kilometres. 


WEIGHTS  AND  MEASURES— WINE  519 

WEIGHTS  AND  MEASURES  (Continued)— 

The  factor  for  the  conversion  of  the  American  gallon 
into  the  British  is  0-834. 

"  WELDON  PROCESS  "  is  one  for  the  recovery  of  the  manganese 
from  the  manganous  chloride  resulting  from  the  manu- 
facture of  chlorine  (see  p."  109),  in  the  form  of  manganese 
dioxide  or  its  equivalent,  for  use  over  again.  The  liquor  is 
treated  with  an  excess  of  milk  of  lime  and  air  blown 
through  the  mixture,  and  in  this  way,  the  manganese 
hydroxide  is  converted  mainly  into  a  combination  of  man- 
ganese dioxide  with  calcium  oxide,  forming  the  Weldon 
mud. 

WELSBACH  LIGHT— See  Light,  p.  292. 

WHALE  OIL— See  Fish  Oils. 

WHATMAN  EXTRACTION  THIMBLES— See  Filters 

WHISKY — Spirit  distilled  from  the  fermented  wort  prepared 
from  malted  barley  dried  over  a  peat  fire ;  in  other  words, 
"  a  spirit  distilled  from  a  mash  of  cereal  grains  saccharified 
by  the  diastase  of  malt." 

WHITE  ARSENIC— Arsenious  oxide,     (See  Arsenic.) 

WHITE-DAMP— See  Coal. 

WHITE-LEAD— See  Lead. 

WHITE  VITRIOL— A  commercial  name  for  zinc  sulphate. 

WHITING— A  purified  preparation  of  chalk. 

WILLESDEN  PAPER— See  Cellulose  and  Copper,  p.  137. 

WINE — The  fermented  juice  of  grapes  (of  which  there  are 
some  600  varieties),  the  colour  of  which  depends  upon 
that  of  their  husks  if  and  when  they  are  included  in  the 
making.  Red  grapes  can  be  made  to  give  yellow  or  white 
wines  if  the  husks  be  excluded,  as  in  the  cases  of  sherry  and 
champagne.  The  flavour  and  other  characters  of  wines 
depend  not  only  upon  the  kind  of  grapes  from  which  they 
are  made  but  also  upon  the  soil  on  which  they  are  grown, 
and  upon  the  ethereal  bodies  resulting  from  changes 
that  take  place  upon  keeping.  Dry  wines  contain  little  or 
no  sugar ;  sweet  wines  contain  sugar  in  greater  or  less  pro- 
portion ;  while  effervescent  wines  like  sparkling  Moselle  and 
Champagne  contain  sugar  in  a  state  of  fermentation,  or  are 
effervescent  as  the  result  of  fermentation  that  takes  place 
after  bottling.  They  all  contain  alcohol  as  a  natural 
product  of  the  fermentation  by  which  they  are  produced, 


520  WINE—WOOD 

WINE  (Continued}— 

the  ferments  consisting  of  the  so-called  "  bloom  "  or  living 
organisms  that  grow  on  the  husks. 

Alcohol  is  added  to  many  wines,  such  as  port  and  sherry, 
and  some  of  the  Australian  and  Californian  wines,  in  order 
to  "  fortify  "  them,  as  it  is  termed,  against  the  acetic  change 
that  might  otherwise  subsequently  take  place  of  the  smaller 
natural  content  of  alcohol  into  acetic  acid.  The  alcoholic 
strength  of  wines  is  by  no  means  constant,  but  as  sold,  it  may 
be  said  that  port  contains  from  14  to  23  per  cent. ;  sherry 
from  14  to  1 8  per  cent. ;  claret  from  6  to  12  per  cent.  ; 
Rudesheimer  and  other  light  wines  about  8  or  9  per  cent.  ; 
beer,  5  to  6  per  cent. ;  small  beer,  2  per  cent.  (See  Yeasts.) 

It  is  said  that  to  produce  good  wines,  the  grape  juice 
must  contain  not  less  than  20  per  cent,  glucose,  but  not 
infrequently,  sugar  is  added  to  the  "  must "  or  expressed 
juice  of  the  grapes. 

In  addition  to  alcohol,  wines  contain  in  many  cases 
small  quantities  of  sugar,  acids  (including  tartaric  acid), 
and  so-called  extractive  matter  of  indefinite  composition. 
Old  wines,  particularly  port,  are  apt  to  deposit  acid  potas- 
sium tartrate  upon  long  keeping.  (See  Tartar.) 

WINTERGREEN  (OIL  OF)— See  Gaultheria  Oil. 
WITHERITE— Natural  barium  carbonate. 

WOAD — Blue  colouring  matter  prepared  from  the  leaves  of 
Isatis  tinctoria,  which  contains  indican  and  is  chemically 
identical  with  indigo. 

WOLFRAM— See  Tungsten. 

WOLFRAMITE— See  Tungsten. 

WOLLASTONITE— A  natural  calcium  silicate  (CaSiO3). 

WOOD — The  wood  from  various  species  of  trees  varies  in 
structure,  specific  gravity,  elasticity,  and  strength.  White 
pine  has  an  average  sp.  gr.  of  0*39,  larch  a  sp.  gr.  of  0-51, 
and  teak  a  sp.  gr.  of  0-66. 

Wood  consists  of  a  mass  of  cells  possessed  of  walls  and 
containing  a  great  variety  of  substances,  such  as  cellulose, 
starch,  resinous  matters,  essential  oils,  etc.  All  woods  are 
liable  to  the  attacks  of  fungus  and  the  decomposition  known 
as  dry  rot.  (See  Dry  Rot.)  More  than  seventy  different 
kinds  of  moulds  and  fungi  have  been  isolated  f j  om  wood 
.or  wood-pulp.  In  spruce,  hemlock,  balsam,  and  aspen, 
the  progress  of  decay  is  distinctly  indicated  by  a  decrease 


WOOD  521 

WOOD  (Continued)— 

in  the  content  of  stable  cellulose  and  increase  in  that  of 
unstable  cellulose. 

The  distillation  or  carbonization  of  wood  is  conducted  in 
cast-iron  retorts,  and  is  now  a  large  industry,  yielding  four 
prime  products  in  addition  to  the  gases  which  are  generated 
— namely,  charcoal  (which  is  left  behind  in  the  retorts), 
acetic  acid  (which  is  recovered  as  acetate  of  calcium  from 
the  pyroligneous  acid  contained  in  the  watery  distillate), 
wood  or  methyl  alcohol,  and  tar.  Wood  creosote  is  ob- 
tained from  the  redistillation  of  the  tar.  (See  Creosote 
(Wood).) 

The  gases  consist  of  about  15  per  cent,  hydrogen,  n  per 
cent,  methane,  26  per  cent,  carbon  dioxide,  41  per  cent, 
carbon  monoxide,  and  7  per  cent,  hydrocarbons. 

Wood  rich  in  rosin,  such  as  that  from  pine-trees,  yields 
also  turpentine,  and  by  pushing  the  distillation  further,  the 
rosin  contained  in  the  wood  yields — 

Rosin  spirit  distilling  between    80°  and  150°  C. 
Rosin  pine  oil     ,,  „         175°    „    250°  C. 

Blue  rosin  oil      „  ,,         250°    ,,    400°  C. 

The  following  represents  the  results  of  a  recently 
published  analysis  of  oak-wood  (Quevcus  agrifolia) : 

Per  Cent. 
Loss  on  drying  ...  ...  ...       4*20 

Benzene  extract  ...  ...  ...       0*50 

Alcohol        „  ...  ...  ...       4-33 

Water          „  ...  ...  ...       3-66 

Soluble     in     cold     5     per     cent,     sodium 

hydroxide  solution     ...  ...  ...  18*71 

Cellulose          ...  ...  ...  ...  45*48 

Lignin  ...  ...  ...  ...  20*25 

Pentosans  not  otherwise  accounted  for      ...       1-89 

Mannan  (residual)         ...  ...  ...  None 

Galactan       ,,  ....          ...  ...       1-49 

100-51 

Green  wood  contains  from  40  to  60  per  cent,  water,  and 
ordinary  dried  woods  contain  about  50  per  cent,  carbon, 
6  per  cent,  hydrogen,  40  to  42  per  cent,  oxygen,  and  i  per 
cent,  nitrogen. 

The  following  compilation  of  various  wood -distillation 
products  produced  in  Canada  in  1918  is  published  by  the 
Canadian  Bureau  of  Statistics  : 


522  WOOD—WORMSEED  OIL 

WOOD  (Continued)— 

Wood  alcohol  (crude,  and  sold  as  such)  875,024  gals. 

„   ^     (refined,       „           „         )  1,070,928    „ 

Acetate  of  lime  ...         ...         ...         ...  25,998,139^35. 

Acetic  acid          ...         ...         ...         ...  1,772,223 

Acetate  of  sodium         295,572 

Acetone ...  3,458,810 

Formaldehyde 1,154,902 

Ketone  oils          ...         ...         ...         ...  792,864 

Acetic  anhydride            ...         ...         ...  44,981 

Methyl  acetate    ...         ...         ...         ...  132,121 

Charcoal...         ...         ...         ...         ...  6,472,925  bush. 

and  other  miscellaneous  products  of  a  total  collective  value 
of  $7,235,217- 

WOOD  FIREPROOFING— See  Fireproofing  (Wood). 

WOOD  OIL— See  Tung  Oil. 

WOOD-PULP  is  prepared  for  use  in  the  manufacture  of  paper 
and  artificial  silk  by  a  number  of  processes — •"  mechanical," 
"  semi-chemical,"  "  sulphite,"  "  sulphate,"  "  soda,"  and  so- 
called  "  kraft  " — all  being  directed  to  obtain  the  constituent 
cellulose  dissociated  from  its  accompanying  substances. 
(See  Paper.) 

WOOD-SPIRIT  or  METHYL  ALCOHOL  (CH3OH)— So  named 
from  its  derivation  from  wood  tar,  particularly  beech- 
wood  tar.  (See  Alcohols,  p.  14.) 

WOOD'S  FUSIBLE  METAL— See  Bismuth. 

WOOL  PITCH  is  the  still  residue  from  distillation  of  wool 
grease  and  wool  fat,  the  stills  being  usually  finished  off 
at  between  600°  and  700°  F.  It  is  odourless,  and  made  in 
several  forms — liquid  to  medium  hard,  the  harder  quality 
melting  at  about  100°  F.  It  is  used  chiefly  for  making  hot 
neck  greases  for  tin-plate  roll  mills;  also  for  insulating 
purposes  and  in  paper-manufacturing. 

WOOL  WAX— See  Waxes. 

WORMSEED  OIL  (Artemisia  Oil)— A  yellowish  essential  oil 
of  unpleasant  odour  with  a  sp.  gr,  of  0-93 ;  soluble  in 
alcohol,  ether,  etc.,  and  distilled  from  the  unexpanded 
flower-buds  of  the  Artemisia  maritima  L.  (South  Russia  and 
the  Levant).  It  contains  cineol,  dipentene,  terpineol,  etc. 
An  American  variety  is  derived  from  the  seeds  of  Cheno- 
podium  ambrosioides,  and  contains  cymene,  sylvestrene, 
camphor,  etc. 


WORM  SEED  OIL—XYLENOLS  523 

WORMSEED  OIL  (Continued)— 

Artemisia  Anmta  is  stated  to  contain  a  ketonic  body 
which  upon  oxidization  yields  a  substance  of  the  formula 
C10H16O,  of  sp.  gr.  0-871,  boiling-point  182°  C.,  and  refrac- 
tive index  1-4688. 

WORMWOOD  (and  WORMWOOD  OIL)— A  very  bitter  herb 
(Artemisia  absinthia)  reputed  as  having  some  medicinal 
value.  The  oil  obtained  by  distillation  is  of  a  greenish 
colour,  contains  thujone,  phellandrene,  etc.,  and  is  soluble 
in  alcohol  and  ether ;  sp.  gr.  about  0*925  to  0-96  ;  refractive 
index,  1-46.  (See  Absinthe.) 

WORT — See  Alcohol,  Beer,  and  Whisky. 

WOULFE'S  BOTTLES  are  provided  with  two  or  more  necks, 
and  an  illustration  will  be  found  under  heading  of  Pneumatic 
Trough.  (See  p.  386.) 

WULFENITE— Crystalline  lead  molybdate  (PbMoO4)  found 
in  some  of  the  United  States  of  America,  etc.  (See 
Molybdenum.) 

WURTZITE — A  native  crystalline  variety  of  zinc  sulphide 
found  in  Montana,  Utah,  etc. 

XANTHINE  (C5H4N4O2)— A  white  amorphous  substance  nearly 
allied  to  uric  acid,  from  which  it  is  obtainable  by  processes 
of  reduction. 

XANTHOPHYLL  —  See  Chlorophyll  and  Plant  Colouring 
Matters. 

XENON  (X) — Atomic  weight,  130*2 ;  sp.  gr.,  4-52.  A  very 
rare  element,  being  one  of  the  so-called  argon  group  of 
atmospheric  gaseous  constituents  isolated  during  recent 
years  and  contained  in  the  heavier  portion  of  liquefied  air. 
It  is  calculated  to  be  present  in  the  air  to  the  extent  of 
i  part  by  volume  in  170,000,000  parts  only.  It  gives  a 
characteristic  spectrum,  is  less  volatile  than  argon,  and  has 
a  density  of  -  0-65.  It  boils  at  -  109-1°  C.,  at  which  tem- 
perature its  density  is  3  -063. 

XYLENE  (Xylol)  (C8H10  or  C6H4(CH3)2)— A  constituent  hydro- 
carbon of  coal  naphtha.  It  is  a  colourless  liquid  of  faint 
odour  distinct  from  that  of  benzene,  of  which  it  is  a  homo- 
logue.  The  crude  article,  of  sp.  gr.  about  0*86  to  0-89,  is 
used  as  so-called  "  naphtha  solvent,"  and  as  a  raw  material 
in  the  manufacture  of  dyes.  In  point  of  fact,  there  are 
three  isomeric  xylenes,  that  from  coal  tar  consisting  of  a 
mixture  of  all  three  kinds.  They  are  all  colourless,  mobile 
liquids,  soluble  in  alcohol  and  ether.  (See  Coal  and  Naphtha. ) 

XYLENOLS  (C8H10O  or  (CH3),C6H3,OH)— Phenolic  com- 
pounds of  high  boiling-point  of  which  some  six  modifications 


524  XYLENOLS—  YEA  STS 

XYLENOLS  (Continued)— 

are  known,  forming  part  of   the  constituents  of  so-called 
"  phenoloids  "  from  blast  furnaces. 

One  of  the  xylenols  is  said  to  be  a  white,  crystalline 
substance,  soluble  in  water  and  alcohol. 

XYLIDINES  (Meta,  Orfcho,  and  Para)— Liquid  amines,  used  in 
dyestuffs. 

The  meta  compound  (C6H3(CH3)2NH2)  is  a  colourless 
oil  which  boils  at  215°  C.,  and  of  sp.  gr.  0-9184. 

The  ortho  compound  (C6H3(NH2)(CH3)2)  is  a  yellow 
liquid,  which  boils  at  about  212°  C.,  and  of  sp.  gr.  981 
to  984. 

The  para  compound  (C6H3(CH3)2NH2)  can  be  obtained 
in  white  crystalline  and  oily  forms,  of  boiling-point  215°  C., 
and  sp.  gr.  0-980. 

All  are  soluble  in  alcohol  and  ether. 

XYLONITE— See  Celluloid. 

X  BAYS — See  Radio-activity  and  Rontgen  Rays. 

YACCA  GUM  is  a  resin  from  Xanthorrhcea  hastilis  of  Australia. 
It  is  soluble  in  alcohol,  but  insoluble  in  turpentine,  linseed 
oil,  benzol,  and  hydrocarbon  solvents  generally,  but  dis- 
solves readily  in  aqueous  caustic  alkaline  solutions  to  deep 
red  solutions,  from  which  it  can  be  reprecipitated  by  acids 
in  a  yellow  flocculent  form.  It  was  an  old  source  of  picric 
acid,  of  which  it  can  be  made  to  yield  15  per  cent.,  has 
been  used  in  the  manufacture  of  dyes,  and  is  said  to  be  of 
importance  in  the  manufacture  of  linoleum,  dyestuffs,  and 
photographic  chemicals. 

YEASTS — Ordinary  yeast  (Saccharomyces  cevevisia)  consists  of 
microscopic  round  or  oval  vegetable  cells  of  about  j--^  inch 
in  diameter  which  multiply  by  gemmation  or  budding,  and 
is  employed  in  various  processes  of  fermentation — wines, 
beers  and^spirits — as  also  in  bread-making.  Fermentation 
induced  by  yeast  can  only  take  place  between  3°  and  35°  C., 
and  the  organism  is  killed  by  a  greater  alcoholic  strength 
than  represented  by  a  solution  of  14  per  cent.  It  loses 
its  activity  when  dried  and  heated  to  60°  C.  or  exposed 
to  the  action  of  antiseptics.  The  fermentation  induced 
by  yeast  is  independent  of  the  cell  walls,  and  is  really 
due  to  the  enzyme  termed  zymase  present  in  their  contents. 
Brewery  yeast  has  a  considerable  food  value,  and  a  food 
is  now  prepared  from  it  resembling  meat  extract  in  flavour. 
There  are  many  varieties  of  yeast  of  distinctive  properties. 
Recently  a  process  has  been  perfected  in  Germany  for 


YEA  STS— YTTRIUM  525 

YEASTS  (Continued)— 

inoculating  waste  liquors  from  sugar  refineries,  distilleries, 
paper  and  starch  works,  with  a  particular  variety  which 
grows  quickly  and  does  not  produce  alcohol.  The  yeast 
increases  in  quantity  at  the  expense  of  the  carbohydrates  in 
the  waste  water  and  added  ammonium  salts,  and  is  ulti- 
mately separated  and  dried. 

It  is  stated  that  100  parts  of  sugar,  or  its  equivalent, 
present  in  the  waste  and  37-5  parts  of  nutritive  ammonium 
salts  yield  150  parts  of  compressed  yeast,  which,  after  dry- 
ing, contains  from  40  to  60  per  cent,  of  albuminous  matter. 

This  dried  yeast,  so  rich  in  nitrogenous  matter,  is  used 
as  cattle  fodder,  and  is  reported  as  fit  for  human  food  to 
replace  a  large  proportion  of  the  necessary  albuminoids. 
(See  also  Enzymes  and  Zymase.) 

YLANG-YLANG— A  yellow  essential  oil  distilled  from  the 
flowers  of  Cananga  odorata  (indigenous  in  the  Malay  Archi- 
pelago, and  cultivated  in  the  Philippines)  of  which  varieties 
are  known  as  "  cananga  "  and  "  manila  "  oils.  They  contain 
methyl  and  benzyl  acetates  and  benzoates,  linalool,  geraniol, 
eugenol,  etc.  The  sp.  gr.  of  ylang-ylang  is  given  as  0-9 
to  0-96,  and  its  rotation  -  1 7°  to  50°,  varying  with  the  source 
of  the  oil,  which  is  soluble  in  alcohol  and  ether,  and  is  used 
in  perfumery. 

YOHIMBINE  (CagH^NjjOJ— A  crystalline  poisonous  alkaloid, 
extracted  from  Lorynanthe  yohimbe,  used  in  medicine. 

YOUNG  FUSTIC— The  heartwood  of  a  sumac  (Rhus  cotonus) 
used  in  the  leather  industry. 

YTTERBIUM  or  NEO- YTTERBIUM  (Yb)— Atomic  weight,  173-5. 
A  very  rare  element  found  in  the  mineral  gadolinite  (ytterbite) 
and  associated  with  yttria.  An  oxide  (Yb2O3)  is  known, 
also  a  chloride  (YbCl3)  and  a  sulphate  (Yb2(SO4)3). 

YTTRITE— Gadolinite. 

YTTRIUM  (Yt)— Atomic  weight,  887 ;  sp.  gr.,  3-80 ;  and 
melting-point,  1,250°  C.  A  very  rare  element  found  in 
gadolinite  (ytterbite),  xenotimmne,  and  samarskite.  Like  ytter- 
bium it  is  associated  with  the  boron  group  of  elements. 
It  is  a  greyish-black  powder  which  is  capable  of  decomposing 
water  to  some  slight  extent  at  the  ordinary  temperatures 
and  more  rapidly  when  heated,  forming  the  oxide  Yt2O3, 
from  which  the  metal  can  be  obtained  by  electrolysis. 
It  is  very  soluble  in  acids,  and  in  addition  to  the  oxide,  a 
number  of  compounds  are  known,  including  a  carbonate 


526  YTTRIUM—  ZINC 

YTTRIUM  (Continued}— 

(Yt2(C03)3),  chloride  (YtCl3),  bromide  (YtBr3),  iodide  (YtI3), 
nitrate  (Yt(NO3)3),  and  sulphate  (Yt2(SO4)3),  all  of  which 
excepting  the  carbonate  are  more  or  less  soluble  in  water. 
The  compounds  of  yttrium  closely  resemble  the  aluminium 
compounds,  and  are  used  in  the  manufacture  of  incan- 
descent gas  mantles. 

ZARATITE  —  A  kind  of  nickel  carbonate  ore. 

ZEOLITES  (Zeoliths)  are  natural  deposits  of  an  opaque  vitreous 
character  abundantly  diffused  in  nature,  which  may  be 
described  as  double  hydrated  silicates  of  aluminium  and 
calcium.  When  treated  with  acids  they  partially  dissolve, 
leaving  the  silica  in  a  gelatinous  state.  Stilbite  and  analcime 
are  two  zeolites.  (See  Permutit.) 

ZINC  (Zn)  and  its  Compounds  —  Atomic  weight,  65  ;  sp.  gr., 
about  6-9  ;  melting-point,  419*4°  C.  Zinc  is  not  met  with 
in  nature  in  the  metallic  state,  but  occurs  as  calamine,  or 
zinc  spar  (zinc  carbonate,  ZnCO3),  in  Silesia  and  the  United 
States  of  America,  and  it  is  also  worked  in  Belgium.  Blende 
(zinc  sulphide,  ZnS)  is  found  and  worked  to  some  extent 
in  England,  while  in  New  Jersey  a  red  zinc  oxide  (ZnO),  the 
colour  of  which  is  due  to  manganese,  is  found  in  consider- 
able amount.  Zinc  also  occurs  in  franUinite  (a  compound 
oxide  of  zinc  and  iron),  in  gahnite  (a  compound  oxide  of  zinc 
and  aluminium),  and  a  number  of  other  minerals.  The 
chief  supply  of  spelter  (as  zinc  is  also  known)  comes  from 
Australia,  and  is  sufficient  to  meet  all  British  wants.  (See 
also  Marmatite.) 

Zinc  boils  at  930°  C.,  and  can  be  distilled  at  1,040°  C. 
It  is  a  crystalline  metal,  has  a  bluish-white  appearance, 
is  fairly  ductile  and  malleable,  and  only  tarnishes  slightly  in 
moist  air.  Evidence  pointing  to  the  existence  of  three  allo- 
tropic  forms  of  the  metal  is  on  record.  It  forms  alloys 
with  tin,  copper,  and  antimony  in  all  proportions,  and  is  a 
component  part  of  many  others  containing  lead  and  bismuth. 
Brass  is  composed  of  2  parts  copper  and  i  part  zinc. 

The  zinc  of  commerce  is  partly  produced  by  a  process 
of  distillation  from  a  mixture  of  the  oxide  of  that  metal 
with  carbon  — 


the  ores  being  first  roasted  so  as  to  convert  any  carbonate 
or  sulphide  into  the  oxide.  There  is,  however,  an  electrical 
process  of  manufacturing  the  metal,  applicable  even  to 
complex  and  low-grade  ores,  which  are  not  amenable  to 
the  distillation  process,  depending  upon  the  electrolysis 


ZINC  AND  ITS  COMPOUNDS  527 

ZINC  (Continued)— 

of  a  solution  of  the  sulphate  (produced  by  dissolving  the 
metal  out  of  the  roasted  ore  by  sulphuric  acid).  In  this 
process,  electrodes  of  lead  and  aluminium  are  used,  the 
zinc  being  deposited  on  the  cathode  (aluminium  pole),  and 
subsequently  stripped  off  and  melted  into  ingots  of  99^95 
per  cent,  purity. 

The  metal  is  largely  used  for  the  production  of  brass, 
roofing,  as  a  lining  for  packing  cases,  making  alloys,  and 
for  galvanizing  (coating)  iron,  to  which  it  gives  durability 
by  preserving  it  from  atmospheric  oxidation. 

Zinc  Oxide  (ZnO)  (zinc  white)  is  produced  as  a  soft  white 
powder  when  the  metal  is  burnt  in  the  air.  It  is  insoluble  in 
water,  and  is  used  in  medicine  and  as  a  pigment,  having 
the  advantage  of  not  being  blackened  by  exposure  to  the  air 
when  sulphuretted  hydrogen  is  contained  therein.  The 
hydroxide  (Zn(HO)2)  is  produced  in  a  white  flocculent 
form  when  an  alkaline  hydrate  is  added  to  a  solution  of  a 
zinc  salt.  It  is  soluble  in  an  excess  of  alkali. 

Zinc  Acetate  (Zn(C2H3O2)2.3H2O)  is  a  white,  crystalline 
salt,  soluble  in  water,  used  as  a  mordant  in  dyeing. 

Zinc  Dichromate  (ZnCr2O7)  is  an  orange-coloured  powder, 
insoluble  in  water,  used  as  a  pigment. 

Zinc  Fluoride  (ZnF2)  is  a  white  powder,  insoluble  in 
water,  used  in  the  ceramic  industries. 

Zinc  Chloride  (ZnC12)  is  prepared  by  dissolving  the  metal 
in  hydrochloric  acid  and  concentrating  to  that  state  in 
which  it  solidifies  upon  cooling,  when  it  is  cast  into  sticks. 
It  is  a  deliquescent  soft  compound  very  soluble  in  water, 
and  can  be  distilled  without  decomposition.  Commercially 
it  is  also  prepared  in  the  form  of  a  strong  solution  of  io2°Tw., 
and  is  used  in  connection  with  soldering  and  as  a  wood 
preservative,  while  a  paste  consisting  of  a  mixture  of  the 
chloride  with  zinc  oxide  is  employed  in  dentistry,  under 
the  name  of  "  oxychloride,"  as  a  stopping  for  teeth. 

Zinc  Sulphate  is  manufactured  by  roasting  the  mineral 
sulphide  under  careful  conditions  and  dissolving  out  the 
sulphate  thus  produced,  and  can  also  be  obtained  by  dis- 
solving the  metal  in  dilute  sulphuric  acid.  It  crystallizes 
with  water  in  combination  as  ZnSO4,7H2O,  is  very  soluble 
in  water,  and  somewhat  efflorescent.  It  becomes  anhydrous 
upon  heating  to  about  300°  C.,  and  is  decomposed  at  a 
higher  temperature  into  sulphur  dioxide,  oxygen,  and  zinc 


528  ZINC— ZIRCONIUM 

ZINC  (Continued)— 

oxide.  It  is  a  particularly  poisonous  salt,  and  finds  use  in 
medical  practice  as  an  astringent  and  antiseptic,  and  as  a 
mordant  in  calico-printing. 

Zinc  Sulphide  (ZnS),  when  precipitated  from  a  solution 
of  a  zinc  salt  by  addition  of  an  alkaline  sulphide  solution 
or  passage  of  hydrogen  sulphide,  is  a  practically  white 
amorphous  substance  insoluble  in  acetic  acid,  and  is  used 
to  some  extent  as  a  pigment  in  place  of  white-lead.  (See 
Lithopone.) 

Zinc  Carbonate  (ZnCO3)  in  dry  form  is  a  white  amorphous 
powder,  insoluble  in  water,  and  used  as  a  pigment  and  in 
medicine,  whereas  Zinci  carbonas  of  the  Pharmacopoeia  is 
a  basic  compound  having  the  composition  expressed  by 
ZnC03,2Zn(HO)2,H20. 

All  the  soluble  salts  of  zinc  are  poisonous. 
ZINC-BLENDE— See  Zinc  and  Sulphur. 

ZINC  DUST  (ordinary  commercial)  is  a  fine  grey  powder 
susceptible  of  rapid  oxidation  and  firing ;  in  great  request 
in  dyeworks  as  a  reducing  agent.  It  consists  of  40  per 
cent,  zinc,  2^  per  cent,  lead,  4  per  cent,  cadmium,  50  per 
cent,  zinc  oxide,  and  3^  per  cent,  zinc  carbonate. 

ZINC-COPPER  COUPLE— Zinc  coated  with  metallic  copper, 
capable  of  decomposing  water  at  its  boiling-point  with 
evolution  of  hydrogen  and  formation  of  zinc  oxide.  It  can 
also  be  employed  to  break  up  a  number  of  organic  liquids 
by  electrolytic  action. 

"  ZINC  FOEMOSUL  "  is  described  as  basic  zinc  formaldehyde 
sulphoxylate,  being  a  greyish-white  powder,  insoluble  in 
water,  but  which  exercises  reducing  power  when  boiled 
with  very  dilute  acids,  or  at  high  temperatures  in  their 
absence.  It  is  advocated  for  use  in  the  autoclave  and 
Twitchell  processes  of  fat  splitting,  and  is  claimed  to  assist 
in  the  bleaching  of  the  resulting  glycerine. 

ZIRCONIUM  (Zr)— Atomic  weight,  90-6;  sp.gr.,  6-4;  melting- 
point,  between  1,530°  and  2,000°  C.  Zirconium  is  a  rare 
element  found  in  nature  in  the  form  of  silicate  (ZrSiO4) 
in  the  mineral  zircon,  and  obtained  by  reduction  of  the 
oxide.  When  metallic  zirconium  is  heated  in  the  air  it 
oxidizes  slowly.  Zirconium  is  soluble  in  hot  acids,  and  one 
method  of  preparing  it  free  from  iron  and  alumina  is  based 
upon  the  production  of  a  basic  sulphate  (5ZrO2.2SO3). 
The  hydroxide  Zr(OH4),  like  the  oxide,  is  insoluble  in 
water,  and  loses  2H2O  at  550°  C. 


ZIRCONIUM— ZYMA  SE  529 

ZIRCONIUM  (Continued)— 

It  belongs  to  the  same  group  of  elements  as  titanium, 
and,  like  silicon,  it  is  known  both  in  crystalline  and 
amorphous  forms.  There  are  several  nitrates,  including 
the  normal  salt  (Zr(NO3)4)  and  a  sulphate  (Zr(SO4)2), 
which  are  soluble  in  water,  a  chloride  (ZrCl4),  which  is  de- 
composed by  water  but  is  soluble  in  alcohol,  and  a  number 
of  other  compounds  bearing  a  resemblance  to  those  of 
thorium  and  silicon. 

Zirconium  Acetate  (Zr(C2H3O2)3OH)  is  a  white,  crystal- 
line, soluble  salt,  used  for  weighting  silk. 

Zirconium  Carbide  (ZrC2)  decomposes  water  and  finds 
use  as  an  abrasive. 

Zirconium  Oxide  (ZrO2)  is  a  heavy,  white,  amorphous 
powder,  obtained  by  heating  the  hydroxide  Zr(OH)4,  and 
is  a  valuable  refractory  material  which  finds  application 
not  only  in  the  preparation  of  incandescent  gas  mantles, 
but  as  an  abrasive,  in  ceramics,  and  in  the  compounding 
of  refractory  and  acid-proof  utensils  and  enamels. 

During  the  recent  war,  zirconium  in  small  amount 
(0*34  per  cent.)  was  introduced  into  the  steel  used  by  the 
French  in  making  armour-plate,  as  in  association  with 
3  per  cent,  of  nickel  it  was  found  to  add  to  its  tensile 
strength. 

A  silvery  white  crystalline  alloy  of  zirconium  with 
aluminium  has  been  prepared  of  the  composition  Zr3Al4. 

ZIRCONS — Natural  silicate  of  zirconium  (ZrSiO4)  found  in 
Brazil  and  elsewhere.  One  such  deposit,  known  as  brazilite, 
is  said  in  a  semi-manufactured  form  to  contain  about  80  per 
cent,  zirconium  oxide.  This  product  is  employed  as  a  re- 
fractory in  the  making  of  "  zirkite  "  bricks  and  cement. 

Another  Brazilian  deposit  is  known  as  orvillite,  and 
contains  about  72  per  cent.  ZrO2. 

ZYMASE  (Invertase  or  Invertin) — An  enzyme  produced  by 
yeast  cells  and  contained  therein,  which  is  capable  of  in- 
ducing fermentative  and  hydrolytic  changes  independently 
of  the  cells.  Sometimes  the  plural  term  zymases  is  used, 
as  meaning  the  same  thing  as  enzymes,  but  that  should 
be  avoided.  (See  Enzymes,  Fermentation,  Invertase,  and 
Yeasts.) 


34 


530  ACICULAR—BARM 


ADDENDA 

ACICULAR  (Crystals) — Needle-shaped. 

ACIDIMETRY — The  determination  of  amount  of  acid  con- 
tained in  a  solution,  by  titration  with  a  standard  alkali 
solution.  (See  Volumetric  Analyses.) 

ACYL  RADICALS— The  radicals  left  after  removal  of  OH 
from  organic  acids  —  for  example,  CH3.CO.  (acetyl), 
C2H5.CO.  (propionyl),  etc. 

ALIPHATIC — The  distinctive  term  applied  to  all  carbon 
compounds  with  open  chains  (as  those  derived  from  the 
paraffin  and  olefine  hydrocarbons),  as  distinct  from  those 
containing  an  aromatic  nucleus.  The  fatty  acids  are,  for 
example,  members  of  the  aliphatic  series.  (See  Chains.) 

ALIQUOT — A  definite  proportion  of  a  given  quantity. 

ALKIMETRY — The  determination  of  amount  of  alkali  con- 
tained in  a  solution,  by  titration  with  a  standard  acid 
solution.  (See  Volumetric  Analyses.) 

ALKYLENES— The  divalent  residues  OH2W.     (See  defines.) 

ALKYLS — The  monovalent  radicals  (C"H2n-f  i)  of  the  mono- 
valent  alcohols  like  methyl  and  ethyl. 

AMMETER — An  instrument  for  determining  the  strength  of 
electrical  currents  in  terms  of  amperes. 

AMPERE — The  unit  of  electrical  current  which,  when  passed 
through  a  solution  of  silver  nitrate  in  water,  causes  the 
deposition  of  silver  at  the  rate  of  ox>oiu8  grm.  per 
second. 

AROMATIC  COMPOUNDS— Those  derived  from  benzene, 
with  rings  or  closed  chains  of  carbon  atoms. 

ARYLS — The  group  of  aromatic  radicals  ;  aniline  is  typical  of 
the  so-called  arylamines. 

ASYMMETRY — The  want  of  symmetry  in  atomic  arrange- 
ment. 

BALANCE— See  Scales. 
BARM— See  Yeasts. 


BASICITY—  COPPER-ZINC  COUPLE  531 

BASICITY  —  The  number  of  hydrogen  atoms  contained  in  an 
acid  which  can  be  replaced  by  a  base.  (See  Acids.) 

BROWNIAN  MOVEMENT—  See  Colloid. 

CALX  —  The  residual  matter  resulting  from  calcination  of 
mineral  matter. 

CENTIGRADE  (Celsius)—  See  Heat,  p.  241. 
CENTIMETRE—  See  Weights  and  Measures. 

CHAINS  —  Atomic  arrangements  of  several  classes.  Open 
chains  have  terminal  atoms  not  mutually  in  combination,  by 
which,  for  example,  aliphatic  combinations  are  character- 
ized ;  thus,  acetic  acid  is  represented  constitutionally  by 
the  formula 

H  O 


H  0-H 

In  closed  chains,  the  terminal  atoms  are  mutually  combined, 
forming  a  ring,  as  in  benzene  : 

CH 


CH/  \CH 
X/ 


CH 

CHROMOGENS— The  parent  group  of  dyes  formed  from 
chromophores  by  substitution  in  hydrocarbons,  and  when, 
in  addition,  a  strong  basic  or  acid  group  (such  as  NH2  or 
.SO2.OH)  is  also  present,  dyes  are  obtained. 

CHROMOPHORES— The  particular  atomic  groupings  character- 
istic of  coloured  organic  compounds,  such  as  .N  :  N  and 
NO2.  (See  Chromogens.) 

COAGULATION — The  more  or  less  solidification  of  a  "  sol " 
to  a  gelatinous  mass ;  solution  of  egg  albumin  is,  for 
example,  coagulated  by  heating  or  by  precipitation  with 
acetic  acid.  (See  Albumins  and  Colloid.) 

COAL  TAR— See  Coal,  p.  122. 

COPPER-ZINC  COUPLE — An  appliance  consisting  of  zinc  and 
precipitated. copper  deposited  thereon,  used  by  Gladstone 
and  Tribe  in  preparing  methane  from  magnesium  methyl 
iodide  and  in  the  study  of  a  variety  of  other  chemical 
changes  induced  by  the  couple. 


532  COULOMB— DISPERSOIDS 

COULOMB — The  unit  quantity  of  electricity  capable  of  de- 
positing i -ii 75  mgrm.  of  silver,  and  delivered  by  i  ampere 
flowing  in  i  second.  96,540  coulombs  =i  faraday. 

CUBIC  CENTIMETRE— See  Weights  and  Measures. 

CUPOLA — Furnace  such  as  used  for  melting  metals.  (See 
Cupellation.) 

CYANATES— See  Cyanic  Acid. 

CYCLIC — A  term  applied  to  compounds  containing  a  ring  of 
atoms  in  the  nucleus.  Carbocyclic  compounds  are  those  in 
which  the  ring  or  closed  chain  is  composed  entirely  of 
carbon  atoms,  such  as  the  naphthenes  and  the  benzene 
derivatives,  including  naphthalene  and  anthracene.  (See 
Chains.) 

DEACON'S  PROCESS— See  Chlorine,  p.  109. 
DEHYDRATION — The  removal  of  water  from  substances. 

DENITRATION — (i)  The  removal  of  nitrogen  oxides  from 
sulphuric  acid  (see  p.  469). 

(2)  The  removal  or  change  of  the  nitro  group  in  organic 
compounds. 

DEXTRO-ROTATORY — The  power  of  rotating  the  ray  of 
polarized  light  to  the  right.  (See  Invertase,  p.  265,  and 
Polarization,  p.  387.) 

DIACTINIC — The  property  of  transmitting  actinic  rays.  (See 
Actinism.) 

DIAMIDE— See  Hydrazine. 

DI  AMINES — Organic  compounds  containing  two  amino  groups, 
such  as  ethylene  diamine  (CaH4(NH2)2)  (a  colourless  liquid 
of  ammoniacal  odour  which  boils  at  123°  C.). 

DIAZO  GROUP  ( -  N2  - ),  as  it  exists,  for  example,  in  diazo- 
benzene  chloride  (C6H6  -  N :  N  -  Cl). 

DIOXIDES — Compounds  containing  two  proportions  of  oxygen 
to  one  of  base — as,  for  example,  barium  dioxide  (BaO2). 

DIOXIMES — Compounds  containing  two  oxime  groups,  such 
as  benzil  dioxime  (CeH5)2C2(N.OH)2.  (See  Oximes.) 

DISPERSION — (i)  A  term  used  in  connection  with  colloidal 
chemistry.  (See  Colloid.) 

(2)   The  separation  of  light  into  its  different  coloured 
rays. 

DISPERSOIDS— See  Osmosis. 


DISULPHIDES-HEXOSES  533 

BISULPHIDES  —  Compounds  containing  two  proportions  of 
sulphur  to  one  of  base  —  as,  for  example,  carbon  disulphide 
(CS2). 

DYADS  —  See  Valencies. 

DYNE  —  The  unit  of  force  in  the  centimetre-gram-second 
system,  or  that  which,  acting  upon  a  mass  of  I  gram  for 
i  second,  produces  unit  velocity  (i  centimetre  per 
second;. 

ELEOPTENES  —  See  Stearoptenes. 
EMANATIONS—  See  Radio-activity. 

ERG  —  The  unit  of  work  in  the  centimetre-gram-second  system 
of  physical  units,  or  the  work  done  by  the  force  of  i  dyne 
moving  through  i  centimetre.  One  joule  =  io7  ergs. 

ESTERIFICATION  —  The  process  of  formation  of  esters.  (See 
Esters.) 

ETHENYL  —  The  radical  CH3.C  i,  as  it  exists,  for  example,  in 
the  crystalline  base  ethenyl-diphenyl  amidine  — 


NHC6H5. 

ETHIDES  —  Combinations  of  metal?  with  the  radical  ethyl, 
such  as  zinc  ethide  (Zn(C2H5)2). 

ETHYL—  The  radical  CH3CH2,  or  C2H5,  as  contained  in  ethyl 
alcohol  (C2H5HO).  (See  Radicals.) 

FAHRENHEIT—  See  Heat,  p.  241. 
FARADAY—  See  Coulomb. 

FLUOSILICATES—  Salts  of  hydro-fluosilicic  acid  (H2SiF6). 
(See  Silicon,  p.  434.) 

FOOT-POUND—  The  unit  of  work  required  to  lift  a  pound 
mass  through  a  distance  of  i  foot. 

FRAUNHOFER  LINES—  See  Spectroscope,  p.  457. 
GAY-LUSSAC  TOWER—  See  Sulphuric  Acid,  p.  469. 
GLOVER'S  TOWER—  See  Sulphuric  Acid,  p.  469. 

GLUCOSANES  —  Polysaccharoses  which,  upon  hydrolysis,  yield 
hexoses. 

GRAMME  (Gram)  —  See  Weights  and  Measures,  p.  517. 

HEXOSES  —  A  group  of  carbohydrates,  including  dextrose  and 
fructose,  divisible  again  into  other  groups  exhibiting 
variously  the  characters  of  aldehydes  and  ketones. 


534  HISTONES— MELTING-POINTS 

HISTONES — A  certain  class  of  proteins  precipitable  from 
solution  by  ammonia. 

HORSE-POWER— The  unit  of  power  being  equal  to  33,000 
foot-pounds  of  work  per  minute  (see  Foot- Pounds), 
i '34  horse-power  =  i  kilowatt,  and  i  horse-power  =  1-014 
metric  horse-power. 

HUBL  NUMBER— Iodine  value  of  fats  and  oils.  (See  Iodine 
Value,  p.  266.) 

HYDRAZINE  (Diamide)  (N2H4  or  NH2.NH2)— A  colourless 
liquid  which  boils  at  113*5°  C.,  made  by  reduction  from 
nitrosamine.  The  name  is  also  given  to  an  organic  com- 
pound containing  two  amido  groups.  (See  Nitrosamines.) 

IMIDO  (IMINO)  GROUP— The  divalent  group  (:NH).  (See 
Imides,  p.  259.) 

INDAMINES — A  group  of  aniline  dyes  including  "  phenol 
blue  "  ((CH3)2N .C6H4.N  :  C6H4 :  O). 

INDOPHENOLS — A  group  of  aniline  dyes. 

INVERSION — See  Invertase,  p.  265,  and  Walden's  Inversion. 

JOULE — io7  absolute  units  of  work  (ergs)  represented  by  the 
energy  expended  in  i  second  by  i  ampere  in  i  ohm. 
One  joule  "=9-239 1  calories. 

KET08ES — Sugars  containing  the  group  carbonyl  :  C  :  O. 
(See  Metallic  Carbonyls.) 

KILO  (Kilogram) — See  Weights  and  Measures,  p.  518. 

KINETIC  ENERGY — That  possessed  by  a  body  in  virtue  of 
its  motion. 

KINETIC  THEORY— This  assumes  that  gas  pressure  is  due  to 
bombardment  of  moving  particles.  (See  Gases,  p.  218.) 

LACTIDE  (C6H8O4) — An  anhydride  of  lactic  acid  which  melts 
at  125°  C. 

L.33VO -ROTATORY — The  property  of  effecting  the  rotation  of 
a  ray  of  polarized  light  to  the  left.  (See  Invertase,  p.  265, 
and  Polarization,  p.  387.) 

LEUCO  BASES — Colourless  compounds  produced  by  reduction 
of  dyes  which  are  reconverted  by  oxidation  into  dyes. 

MELTING-POINTS — The  temperatures  at  which  fusible  sub- 
stances melt,  or  become  liquid,  and  as  these  are  affected  by 
pressure  they  are  usually  referred  to  normal  pressure 
(760  mm.). 


METABOLISM—OHM  535 

METABOLISM — The  various  changes  resulting  from  the 
conversion  of  food  in  living  organisms 

METHYL— The  monovalent  (univalent)  radical  CH3.  (See 
Alcohol  (Methyl),  p.  14.) 

MINERAL  ACIDS — A  general  name  given  to  all  acids  other 
than  those  of  organic  character. 

MONAD— See  Valencies,  p.  498. 

MUCINS — A  class  of  glyco-proteins  which  occur  in  some  secre- 
tions and  yield  albumin  and  carbohydrate  upon  hydrolysis. 

MYDRIATIC — The  property  of  causing  dilatation  of  the  eye 
pupil,  exhibited  by  a  number  of  substances,  including 
hyoscyamine  and  homatropine. 

MYOTIC — The  property  of  causing  contraction  of  the  eye 
pupil,  exhibited  by  a  number  of  substances,  including 
eserine.  (See  Calabar  Bean.) 

NITROGENIZE — Combination  of  nitrogen  or  nitrogenous 
groups  with  other  substances. 

NITROGENOUS— A  term  applied  to  substances  containing 
nitrogen  as  an  important  constituent,  such  as  fertilizers 
and  proteins. 

NITRO-GROUP  (Nitryl)  (-NO2)—  As  present  in  nitrobenzene 
(C6H5NO2),  for  example. 

NITROMETER — An  apparatus  for  measuring  nitrogen  gas  as 
evolved  from  chemical  interactions. 

NITROSAMINES — A  series  of  yellow,  aromatic,  volatile 
bodies  derived  from  the  secondary  bases  containing  the 
imino  group  :NH  by  treatment  with  nitrous  acid,  such  as 
dimethyl  nitrosamine  (CH3)2N.NO.  (See  Hydrazine.) 

NITROSO  COMPOUNDS  are  those  containing  the  group 
-  N  :  O — as,  for  example,  nitrosobenzene  (C6H5  — NO). 

NITROSYL— The  monovalent  radical  -  N  :  O  as  it  exists  in  a 
number  of  compounds,  such  as  nitrosyl  chloride  (NOC1),  an 
orange-coloured  gas  resulting  from  the  direct  combination 
of  nitric  oxide  with  chlorine. 

NITROXYL — The  monovalent  radical  -NO2  as  it  exists  in 
compounds  such  as  nitroxyl  fluoride  (NO2F),  a  colourless  gas 
resulting  from  the  direct  union  of  fluorine  and  nitric  oxide. 

OHM — The  international  unit  of  resistance  is  that  offered  by  a 
column  of  mercury  106*3  cm>  m  length,  14-452 1  grms.  in 
mass,  and  at  the  temperature  of  melting  ice,  to  an  unvary- 
ing electric  current. 


536  ORGANIC— PRESSURE 

ORGANIC— See  Carbon  and  Organic  Matters,  p.  84, 

ORIENTATION — The  relative  positions  of  substituted  con- 
stituents in  relation  to  the  parent  substances  and  each  other. 

OZONIDES — Combinations  of  ozone  with  unsaturated  hydro- 
carbons and  alcohols — as,  for  example,  ethylene  ozonide 
(C2H4  +  03). 

PENTOSANES — Gums  which  yield  pentoses  upon  hydrolysis — 
as,  for  example,  cherry  gum,  which  yields  /-arabinose. 

PENTOSES — Saccharoid  bodies  containing  five  carbon  atoms, 
such  as  /-arabinose  (C5H6O(OH.)4),  and  which  yield 
furfuraldehyde  or  methyl  furfuraldehyde  when  boiled 
(hydrolized)  with  hydrochloric  acid.  (See  Carbohydrates.) 

PENTOXIDE — An  oxide  containing  five  atoms  of  oxygen  in  the 
molecule — for  example,  phosphorus  pentoxide  (P2O5). 

PEPTIZATION— See  Colloid. 

PHAGOCYTES— Cells  which  destroy  bacteria,  etc.,  in  the 
blood,  and  distinct  from  leucocytes,  which  are  also  said  to 
exercise  phagocytic  activity.  This  last-named  activity  is 
said  to  be  increased  by  other  substances,  known  as 
Opsonins. 

PHENOLATES — Compounds  formed  from  phenols  and  metals 
by  substitution  of  the  hydroxyl  hydrogen — for  example, 
sodium  phenolate  on  phenate  (NaC6H5O),  which  is  made 
by  dissolving  phenol  (C6H5HO)  in  caustic  soda  solution. 

PHENOL  BLUE— See  Indamines. 

PHOSPHORYL— The  trivalent  radical  |  P  :  O,  as  it  exists  in 
combinations  such  as  phosphoryl  chloride  (POC13),  a 
colourless,  fuming  liquid  formed  by  the  action  of  water 
upon  phosphorus  pentachloride,  etc. 

PHTHALEINS — A  group  of  organic  compounds  (dyes)  con- 
taining two  phenol  residues  prepared  by  the  action  of 
phenols  upon  phthalic  anhydride,  including  phenol- 
phthalei'n  and  fluoresce'in.  They  are  nearly  related  to 
another  colourless  group  known  as  "phthalines,"  which 
are  leuco-compounds  of  the  phthalei'ns. 

PLATINAMINES  (Platosammines)— A  number  of  basic  com- 
pounds formed  from  platinum  and  ammonia,  many  of 
which  are  of  complex  character.  One  such  salt  has  the 
composition  Pt(NH3)2Cl2.  (See  also  Platinum,  p.  384.) 

POLARISCOPE— See  Polarization. 

PRESSURE  (Atmospheric) — See  Barometer,  p.  51. 


PROPIONYL-SULPHURYL  537 

PROPIONYL— The    acyl    group,   CH3.CH2.C  :  O,    left    after 
removal  of  HO  from  propionic  acid. 

PROPYL — The  monovalent  radical  group  C3H7,  or  CH3.CH2. 
CH2.     (See  Propyl  Alcohol,  p.  15.) 

PROTAMINES — The  simplest  proteins,  including  salmine  and 
and  sturine,  as  isolated  from  fish  testicles. 

PURINE  GROUP— A   number   of  so-called   cyclic   diureides, 

including  uric  acid. 

QUADRIVALENT— Same  as  tetravalent.     (See  Valencies.) 
QUINTESSENCE — An  extracted  essence  or  essential  oil. 
REAUMUR— See  Heat,  p.  241. 
RED  LIQUOR— See  Aluminic  Acetate,  p.  26. 
RED  OIL — Commercial  oleic  acid. 

RHEOSTATS— Instruments  for  regulating  the  flow  of  electric 
currents  and  for  measurements,  thus  affording  the  means  of 
controlling  the  amount  according  to  Ohm's  law.  (See  Ohm.) 

RHIZOME — Underground  stems  or  roots. 
RING,  BENZENE— See  Chains. 

SAND-BATH — A  laboratory  contrivance  to  secure  a  fairly 
regulated  heat,  consisting  of  an  iron  saucer  containing  a 
thin  layer  of  sand  heated  by  a  lamp  below,  and  on  which 
the  vessel  to  be  heated  is  placed. 

SESQUIOXIDES— Oxides  like  ferric  oxide  (Fe2O3)  in  which 
the  proportions  of  metal  and  oxygen  are  as  two  to  three. 

SORPTION — The  combination  of  water  or  other  liquid  with  a 
curd  or  colloid  body,  as  distinct  from  mere  entanglement. 
(Compare  Colloid  and  Adsorption.) 

SPRENGEL  PUMP— See  Pumps  (Exhaust). 

STEAROPTENES— The  solid  constituents  of  certain  essential 
oils,  the  liquid  parts  being  designated  eleoptenes.  (See 
Attar  of  Roses.) 

STEREO-CHEMISTRY— The  study  of  the  relative  positions 
occupied  by  atoms  or  groups  within  molecular  bodies. 

SUB — A  chemical  prefix  used  to  indicate  a  lower  valency  or 
basic  substances,  such  as  lead  suboxide  (PbO2),  and  the 
subacetate  or  basic  acetate  of  lead  (Pb(C2H,OA, 
Pb(HO)2). 

SULPHURYL — The  divalent  radical  :  SO2  as  occurring,  for 
example,  in  sulphuryl  chloride  (SO2C12),  which  can  be 
prepared  by  the  direct  union  of  chlorine  and  sulphur 


538  SULPHURYL—UREOMETER 

SULPHURYL  (Continued)— 

dioxide.     It  is  a  colourless  liquid  which  boils  at  70°  C. 
and  is  decomposed  by  water,  producing  hydrochloric  and 
sulphuric  acids. 

SULPHONIC  ACIDS  —  Organic  combinations  containing  the 
monovalent  group  .SO2.OH  in  association  with  alkyl  or 
aryl  residues.  (See  Sulphonation.) 

TAWING  —  The  dressing  of  skins,  or  tanning  processes  with 
alum  or  chromium  salts. 

THERMAL  UNIT—  See  Heat,  p.  244. 

THERMOPILE  (Thermocouple)—  An  apparatus  constructed 
upon  the  knowledge  that  an  electric  current  can  be  pro- 
duced in  a  closed  circuit  by  heating  the  point  of  contact  of 
two  dissimilar  metals.  The  electromotive  force  (E.M.F.) 
of  a  bismuth-antimony  pair  when  the  junctions  are  kept  at 
o°  and  100°  is  only  o'Oii5  volt,  but  using  series  of  such 
pairs  so  arranged  that  the  alternate  junctions  can  be 
heated,  the  current  is  increased  proportionally  to  the 
number  of  pairs. 

THIAZOLE  —  An  organic  colourless  liquid,  boiling  at  117°  C., 
represented  by  the  formula 
CH.N 


CH.S 
THIO-ALCOHOLS—  See  Mercaptans. 

TINCTURES—  Alcoholic  solutions  of  drugs  ;  more  dilute  than 
extracts.  (See  Extracts,  p.  192.) 

TOXALBUMINS—  Products  of  protein  nature  which  are 
distinct  from  ptomaines  and  include  the  poisons  of  snake 
bites  and  others  of  plant  origin,  such  as  abrin  (the  poison- 
ous principle  of  Abrus  pvecatomts  —  jequirity)  and  ricin  (a 
poisonous  ingredient  of  the  castor-oil  plant). 

TREE-LEAD  —  The  arboreal  form  of  lead  as  deposited  on  a  bar 
of  zinc  when  placed  in  an  aqueous  solution  of  a  lead  salt, 
or  formed  electrolytically,  as  described  under  Lead,  p.  290. 

ULTRA-VIOLET  RAYS—  Light  rays  forming  part  of  the 
spectrum  so  short  that  the  human  eye  is  not  sensitive  to 
them.  (See  Spectroscope.) 

UREO  METER  —  An  apparatus  for  quantitatively  determining 
urea  contained  in  urine  by  measuring  the  amount  of 
nitrogen  gas  evolved  in  its  decomposition,  using  sodium 
hypobromite  in  sodium  hydrate  solution. 


VINA  SSE—ZYMOGENS  539 

VINASSE — Residue  left  after  fermentation  of  beet  molasses, 
containing  potash  salts  and  some  nitrogenous  matter  which 
qualify  it  for  use  as  a  fertilizer  and  cattle  food.  (Compare 
Begasse.) 

VOLT=io8  absolute  units  is  the  electromotive  force  which, 
applied  to  i  ohm,  will  produce  in  it  a  current  of  i  ampere. 
(See  Ohm.) 

VOLTAIC  CURRENT— See  Electricity. 

WALDEN'S  INVERSION — Concerns  the  conversion  of  optic- 
ally active  substances  into  others  of  opposite  rotation,  such 
as  that  of  /-chlorsuccinic  acid  into  the  rf-isomeride,  and 
/-malic  acid  into  the  ^-malic  acid,  by  means  of  chemical 
reagents.  (Compare  Polarization  and  Racemic  Com- 
pounds.) 

WATT — The  power  of  an  electric  current  of  i  ampere  flowing 
under  a  pressure  of  i  volt,  and  approximately  y^  part  of 
i  horse-power. 

WOOL  FAT — Contains  a  number  of  fats  and  cholesterin. 
(Compare  Adeps  Lanae  and  Suint.) 

ZERO  (Absolute) — See  Notable  Temperatures,  p.  242. 

ZYMOGENS — Substances  from  which  it  is  conjectured  that 
the  enzymes  are  formed  in  the  organism. 


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